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NATURAL  HISTORY 
SURVEY 


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U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  62. 


L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


A 


C.  L.  MARLATT, 

Entomologist  and  Acting  Chief  in  Absence  of  Chief 


Issued  December  5,  1906. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1 906. 


BUREAU  OF  ENTOMOLOGY. 

L.  0.  Howard,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Marlatt,  Entomologist  and  Acting  Chief  in  absence  of  Chief. 

R.  S.  Clifton,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  breeding  experiments. 

A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  cotton  boll  weevil  investigations. 

F.  M.  Webster,  in  charge  of  cereal  and  forage-plant  insect  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous-fruit  insect  investigations. 

Frank  Benton,  in  charge  of  apicultural  investigations. 

D.  M.  Rogers,  in  charge  of  gipsy  and  brovm-tail  moth  work. 

A.  W.  Morrill,  engaged  in  white  fly  investigations. 

E.  A.  Schwarz,  D.  W.  Coquillett,  Th.  Pergande,  Nathan  Banks,  Assistant  Ento- 
mologists. 

E.  S.  G.  Titus,  August  Busck,  Otto  Heidemann,  R.  P.  Currie,  J.  G.  Sanders,  A.  N. 

Caudell,  F.  D.  Couden,  E.  R.  Sasscer,  J.  H.  Beattie,  I.  J.  Condit,  Assistants. 
Lillian  L.  Howenstein,  Frederick  Knab,  Artists. 

Mabel  Colcord,  Librarian. 

H.  E.  Burke,  W.  F.  Fiske,  J.  L.  Webb,  J.  F.  Strauss,  engaged  in  forest  insect  investi- 
gations. 

W.  E.  Hinds,  J.  C.  Crawford,  W.  A.  Hooker,  W.  W.  Yothers,  A.  C.  Morgan, 
W.  D.  Pierce,  F.  C.  Bishopp,  C.  R.  Jones,  F.  C.  Pratt,  C.  E.  Sanborn,  J.  D. 
Mitchell,  Wilmon  Newell,  J.  B.  Garrett,  C.  W.  Flynn,  A.  W.  Buckner,  R.  A. 
Cushman,  W.  H.  Gilson,  engaged  in  cotton  boll  weevil  investigations. 

G.  I.  Reeves,  W.  J.  Phillips,  C.  N.  Ainslie,  engaged  in  cereal  and  forage-plant  insect 
investigations. 

Fred  Johnson,  A.  A.  Girault,  Dudley  Moulton,  engaged  in  deciduous-fruit  insect 
investigations. 

E.  F.  Phillips,  J.  M.  Rankin,  engaged  in  apicultural  investigations. 

C.  J.  Gilliss,  T.  A.  Keleher,  W.  A.  Keleher,  engaged  in  silk  investigations. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  62. 

L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


BY 


C.  L.  MARLATT, 

Entomologist  and  Acting  Chief  in  Absence  of  Chief. 


Issued  December  5,  1906. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1 906. 


it  01'  TRANSMITTAL 


U.  S.  Department  of  Agriculture, 

Bureau  of  Entomology, 
Washington , D.  C.,  August  31,  1906. 

Sir:  I have  the  honor  to  submit  for  publication  a manuscript  enti- 
tled “The  San  Jose  or  Chinese  Scale,”  which  is  a thoro  revision  of 
the  previous  publications  on  this  subject  issued  by  the  Department, 
namely,  Bulletins  Nos.  3 and  12,  new  series,  of  this  office.  In  spite 
of  the  large  number  of  articles  which  have  been  published  concerning 
this  insect  in  experiment  station  bulletins  and  in  journals  and  maga- 
zines, there  is  a distinct  need  for  a comprehensive  treatment  of  this 
most  important  subject,  and  this  need,  I think,  has  been  met  in  an 
excellent  way  by  Mr.  Marlatt  in  this  manuscript.  I recommend  that 
it  be  published  as  Bulletin  No.  62  of  this  Bureau. 

Respectfully, 

L.  O.  Howard, 

Entomologist  and  Chief  of  Bureau. 

Hon.  James  Wilson, 

Sec7%etary  of  Agriculture. 

A 


PREFACE. 


Bulletin  No.  3 (new  series)  of  this  office,  giving  a full  account  of  the 
San  Jose  scale,  was  presented  for  publication,  under  the  joint  author- 
ship of  Doctor  Howard  and  the  writer,  November  29,  1895,  and 
included  the  results  of  two  years  of  very  thoro  study  of  the  San  Jose 
scale.  Two  years  later  Doctor  Howard  issued,  as  Bulletin  No.  12  (new 
series),  a record  of  the  work  to  the  end  of  1897,  more  particularly  giv- 
ing an  account  of  the  spread  of  the  San  Jose  scale  in  the  United  States 
during  the  intervening  period  and  the  results  of  remedial  work  by  this 
office  and  the  different  experiment  stations,  together  with  additions  to 
the  bibliography.  It  has  now  been  more  than  ten  }Tears  since  the 
publication  of  the  larger  bulletin  giving  the  full  life  history  of  this 
scale  pest,  and  it  seems  advisable  to  issue  a new  general  publication 
to  include  in  one  bulletin  the  considerable  additions  which  have  been 
made  to  our  information  on  the  subject. 

The  portion  of  Bulletin  3 giving  the  life  history  of  the  insect  was 
worked  out  with  great  minuteness  and  is  reproduced  with  little  change. 
The  facts  relating  to  the  original  home  of  the  insect,  as  discovered  by 
the  writer  in  1901  in  the  course  of  explorations  in  China  and  Japan, 
are  incorporated  in  this  bulletin,  and  the  distribution  of  the  insect  has 
been  brought  down  to  date. 

The  literature  of  the  last  ten  years  relating  to  the  San  Jose  scale  is 
of  enormous  volume,  probably  exceeding  that  relating  to  any  other 
insect  pest.  Most  of  this  literature  relates,  however,  to  the  strictly 
economic  phase  of  the  subject — namely,  distribution,  injury  to  plants, 
and  the  means  of  control — together  with  legal  enactments  of  various 
foreign  countries  and  of  the  several  States  of  the  Union.  The  listing 
of  all  the  publications  on  the  San  Jose  scale  subsequent  to  its  appear- 
ance in  the  East  in  1893  would  make  a bulletin  of  itself  and  would 
probably  serve  no  very  useful  purpose,  and  therefore  no  bibliography 
is  given  in  this  publication.  The  earlier  writings  on  this  insect  are, 
however,  recorded  in  Bulletins  3 and  12. 

The  early  experimental  work  with  remedies  given  in  Bulletin  3 is 
omitted,  and  no  effort  has  been  made  to  summarize  the  enormous 
body  of  reports  on  work  with  remedies  recorded  in  the  publications 
of  different  experiment  stations  in  this  country.  The  results  of  the 
later  work  with  remedies  conducted  by  this  Bureau  are  to  be  found 

3 


4 


PREFACE. 


in  the  five  different  editions  of  Circular  42,  relating  to  the  control  of 
the  San  Jose  scale,  and  in  the  two  editions  of  Circular  52,  relating  to 
the  lime,  sulfur,  and  salt  wash,  and  also  in  several  articles  in  the  : 
miscellaneous  bulletins  of  the  Bureau. 

Inasmuch  as  a good  deal  of  the  present  bulletin  has  been  rewritten, 
and  as  most  of  the  added  matter  is  from  articles  published  by  the 
writer,  at  the  suggestion  of  Doctor  Howard  this  publication  is  issued 
as  a new  bulletin  of  the  Bureau  series  and  under  single  authorship. 
Considerable  matter,  however,  from  Bulletin  3,  notably  that  relating 
to  life  history  and  habits,  has  been  used,  as  already  indicated,  with 
little  change;  this  publication  is  largely,  therefore,  a compilation,  with 
the  aim  of  bringing  the  subject  down  to  date  and  making  it  complete 
and  available  as  a means  of  present  information  on  the  habits  and 
status  of  this  important  scale  insect  pest. 

The  portion  on  true  parasites  (pp.  58-62)  was  kindly  prepared  by 
Doctor  Howard,  who  has  long  been  the  authority  on  this  group  of 
parasitic  four- winged  fiies. 


C.  L.  M. 


CONTENTS. 


Page. 

Introduction 7 

Present  status  of  the  problem 8 

Origin  of  the  insect 10 

Explorations  in  eastern  Asia 11 

Explorations  in  Japan 11 

Explorations  in  China 13 

Eecord  of  the  spread  of  the  insect 15 

History  in  California  and  the  West 15 

History  in  the  East 16 

Principal  sources  of  infestation  in  the  East 17 

Summary,  by  States  and  Territories,  of  distribution  and  present  condition.  18 

The  relation  of  climate  to  spread 33 

Habits  and  life  history 34 

Nature  of  the  damage 34 

Food  plants 36 

Citrus  fruits  and  the  San  Jose  scale 42 

Life  history 43 

Descriptions  of  scale  and  insect 51 

Systematic  position  and  relationships 54 

Means  of  distribution 56 

Parasites  and  other  natural  enemies 58 

True  parasites  (by  L.  O.  Howard) 58 

Predaceous  insect  enemies 62 

Native  and  introduced  enemies  of  other  scale-insects 62 

The  Asiatic-ladybird  enemy  of  the  San  Jose  scale 62 

Fungous  and  other  diseases  of  the  San  Jose  scale 69 

Means  of  controlling  the  San  Jose  scale 72 

Insecticide  applications 72 

The  lime-sulfur  wash 73 

The  soap  treatment 75 

Kerosene  treatment - 76 

The  oil- water  treatment 77 

Petroleum-soap  emulsions 78 

Fumigation  of  nursery  stock 79 

Legislation  against  the  San  Jose  scale , 80 

Index 81 


5 


ILLUSTRATIONS. 


PLATES. 

Page. 

Plate  I.  The  San  Jose  scale  and  its  work:  Fig.  1. — Peach  tree  with  top  killed 
by  the  scale.  Fig.  2. — Peach  twig,  moderately  infested,  showing 
male  and  female  scale.  Fig.  3. — Peach  limb  badly  infested  with 

scale - 8 

II.  Map  of  China  and  Japan,  to  illustrate  geographical  position  in  relation 

to  native  home  and  distribution  of  San  Jose  scale 12 

III.  Fig.  1. — Japanese  apple  orchard,  showing  trellis  method  of  training. 

Fig.  2. — Old  native  pear  orchard  of  Japan,  showing  method  of 
training 12 

IV.  Fig.  1. — Pony  fruit  cart  in  which  products  of  the  hill  country  are 

brought  into  Pekin,  China.  Fig.  2. — Portion  of  street  devoted  to 

sale  of  fruits  in  Pekin,  China 14 

V.  Life  zones  of  the  United  States 34 

VI.  Fig.  1. — Large  apple  trees  with  lower  limbs  killed  by  the  San  Jose 
scale,  Youngstown,  N.  Y.  Fig.  2. — Apple  infested  with  San  Jose 

scale . *. 34 

VII.  Pupating  larvae  of  Chilocorus  similis  on  the  terminals  of  twigs  in 

Department  orchard 66 

VIII.  Cages  used  in  breeding  Asiatic  ladybird  (Chilocorus  similis) 66 

IX.  Steam  plants  for  cooking  lime-sulfur  wash 74 

TEXT  FIGURES. 

Fig.  1.  Map  of  the  United  States,  showing  localities  known  to  have  been 

infested  with  the  San  Jose  scale  up  to  1896 19 

2.  Aspidiotus  perniciosus:  appearance  of  scale  on  bark 35 

3.  Aspidiotus  perniciosus:  young  larva  and  developing  scale 44 

4.  Aspidiotus  perniciosus:  development  of  male  insect 46 

5.  Aspidiotus  perniciosus:  adult  male 47 

6.  Aspidiotus  perniciosus:  adult  female 48 

7.  Aspidiotiphagus  citrinus 60 

8.  Prospalta  aurantii  61 

9.  Ablerus  clisiocampx:  female : 61 

10.  Microweisea  ( Pentilia ) misella:  adults,  larvae,  pupae 63 

11.  Chilocorus  similis:  oviposition  and  early  larval  stages 65 

12.  Chilocorus  similis:  later  larval  stages,  pupa,  adult 66 


6 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


INTRODUCTION. 

The  San  Jose  scale  is  now  known  to  be  of  Chinese  origin.  Its  name 
is  derived  from  its  first  point  of  colonization  in  America,  namely,  at 
San  Jose,  Cal.,  and  is,  in  a sense,  undesirable,  as  giving  an  unmerited 
notoriety  to  the  district  in  California  which  had  the  misfortune  of 
being  the  accidental  place  to  first  harbor  it.  A more  appropriate  des- 
ignation is  the  Chinese  scale , but  it  is  improbable  that  a new  name  will 
ever  be  adopted  for  an  insect  which  has  become  so  thoroly  well  known 
and  exploited  under  its  original  designation. 

Probably  no  other  insect  has  had  so  much  notoriety  as  has  this  spe- 
cies, and  certainly  none  has  assumed  so  great  an  international  impor- 
tance, as  indicated  by  the  vast  amount  of  interstate  and  foreign 
legislation  which  has  been  enacted  relative  to  it.  In  all  the  earlier 
publications  of  this  office,  beginning  with  Comstock’s  original  descrip- 
tion and  note  in  the  Report  of  the  Department  of  Agriculture  for  1880, 
the  very  great  economic  importance  and  capacity  for  harm  of  this 
scale  insect  has  been  commented  upon  and  the  fact  that  there  is  per- 
haps no  insect  capable  of  causing  greater  damage  to  fruit  interests  in 
the  United  States  than  the  San  Jose  or  pernicious  scale. 

It  is  inconspicuous  and  often  for  a time  passes  unnoticed  or  unrecog- 
nized. Meanwhile  its  enormous  fecundity  enables  it  to  overspread  the 
trunk,  limbs,  foliage,  and  fruit  of  the  tree  attacked  (Pis.  I,  VI),  so 
that  it  is  only  a question  of  two  or  three  years,  unless  proper  remedial 
steps  be  taken,  before  the  condition  of  the  plant  becomes  hopeless  or 
its  death  is  brought  about.  In  capacity  for  harm  this  species  probably 
exceeds  any  other  scale  insect  known,  and  it  attacks  practically  all 
deciduous  plants,  both  those  grown  for  fruit  and  the  ornamentals.  Its 
economic  importance  is  further  increased  by  the  ease  with  which  it  is 
distributed  over  wide  districts  thru  the  agency  of  nursery  stock, 
and  the  difficulty  and,  as  a rule,  impossibility  of  exterminating  it  where 
once  introduced.  Its  capacity  for  evil,  which  was  recognized  in  its 
earlier  work  on  the  Pacific  .coast,  was  at  once  even  more  strikingly 
demonstrated  on  its  first  appearance  in  the  East,  and  before  measures 
of  control  were  undertaken  it  was  much  more  disastrous  in  peach 
orchards  of  Maryland,  New  Jersey,  and  other  eastern  and  southern 
States  than  in  California  and  the  West. 


7 


8 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


PRESENT  STATUS  OF  THE  PROBLEM. 

The  estimates  given  in  our  early  publications  of  the  seriousness  of 
this  pest  have  been  more  than  borne  out  by  the  experience  of  the  last 
ten  years.  Since  its  appearance  on  the  Atlantic  seaboard  in  the  early 
nineties  it  has,  in  spite  of  all  efforts  at  control  in  nurseries  and  by 
State  quarantine,  spread  well  over  the  eastern  and  middle  United 
States  and  into  Canada,  so  that  there  are  now  very  few  regions  where 
fruit  growing  is  at  all  important  in  which  it  has  not  gained  permanent 
foothold.  Maine  and  a few  of  the  middle  western  States  have  not  so 
far  reported  this  scale  insect,  but  it  is  only  a question  of  time  when 
it  will  complete  its  extension  over  the  entire  fruit-growing  areas  of 
North  America  within  its  climatic  range. 

Nevertheless  the  San  Jose  scale  has  not  been  an  unmitigated  scourge, 
and  the  active  investigations  b}7  the  Bureau  of  Entomology  of  the 
United  States  Department  of  Agriculture  and  the  entomologists  of  the 
State  experiment  stations  have  demonstrated  the  practicability  of 
several  means  of  control,  and  particularly  of  the  lime-sulfur  wash;  so 
that  the  fears  aroused  by  this  scale  insect  are  rapidl}T  subsiding  and  it 
no  longer  is  considered  as  an  insurmountable  obstacle  to  the  growth 
of  deciduous  fruits.  In  the  case  of  certain  fruits,  as,  for  example,  the 
peach,  it  has  been  found  that  the  lime-sulfur  wash  has  a very  great 
value  as  a fungicide,  and  so  much  so  that  some  growers  are  recom- 
mending its  use  whether  the  San  Jose  scale  be  present  in  the  orchard 
or  not.  Furthermore,  the  presence  of  this  scale  has  led  to  much  more 
careful  methods  on  the  part  of  mirser}7men  and  in  the  planting  and 
care  of  stock,  thus  raising  the  standard  and  giving  the  intelligent  and 
conscientious,  painstaking  grower  a distinct  advantage  over  his  care- 
less neighbor.  The  results  in  the  East,  in  other  words,  are  following 
rather  closely  on  the  experience  in  California  and  elsewhere  on  the 
Pacific  coast,  where  the  San  Jose  scale,  long  looked  upon  as  the  worst 
menace  of  the  deciduous-fruit  interests,  is  now  not  necessarily  so 
regarded,  and  the  same  benefits  have  come  to  California  fruit  growing 
by  the  use  of  better  methods  of  planting,  pruning,  and  care. 

This  does  not  mean  that  the  San  Jose  scale  is  to  be  lookt  upon  as 
a blessing.  The  benefits  of  spraying  are  not  always  uniform,  and  are 
less  perhaps  in  the  case  of  the  apple  than  they  are  with  the  peach, 
pear,  and  the  smoother  barked  fruit  trees.  The  necessity  of  annual 
spraying  of  the  trees  is  now  clearly  shown,  and  this  amounts  to  a 
very  large  annual  cost,  partly  offset,  as  already  indicated,  by  the  fun- 
gicidal value  of  the  standard  lime-sulfur  application.  Nevertheless, 
neither  the  injuries  from  the  scale  nor  the  cost  of  treatment  have  put 
more  than  a temporary  check  upon  the  advance  of  the  fruit  industry, 
and  great  confidence  is  being  exprest  by  the  larger  commercial  growers 
who  follow  out  the  remedies  with  greatest  thoroness  and  in  the  most 


The  San  Jose  Scale  and  Its  Work. 


Bui.  62,  Bureau  of  Entomology,  U.  S.  Dept,  of  Agriculture. 


Plate  I 


LIBRARY 

university  of  Illinois 

URBANA 


PRESENT  STATUS  OF  THE  PROBLEM. 


9 


practical  manner,  and  who  consequently  get  the  best  results.  It  is 
now  largely  a matter  of  getting  the  owners  of  small  orchards  to 
follow  a regular  annual  system  of  spraying  their  trees. 

The  presence  of  San  Jose  scale  has  not  only  resulted  in  a consider- 
able increase  of  information  as  to  remedies  and  to  improvements  in 
the  methods  of  culture  which  directly  relate  to  itself,  but  it  has  been 
a stimulus  to  improved  methods  and  more  efficient  means  of  control 
of  other  common  destructive  insects,  has  demonstrated  the  necessity 
of  watchfulness  against  the  introduction  of  similar  pests  from  foreign 
sources,  and  has  led  to  active  efforts  in  the  direction  of  quarantine 
and  inspection  on  the  part  of  practically  all  of  the  several  States  of 

the  Union.  • 

The  control  of  the  San  Jose  scale  by  parasitic  and  predaceous  ene- 
mies is  increasing  all  the  time,  but  there  seems  to  be  no  likelihood  that 
either  such  natural  enemies  as  are  now  in  this  country  or  those  which 
mar  hereafter  be  imported  will  ever  do  more  than  merely  lessen  the 
abundance  of  the  scale.  In  other  words,  from  past  experience  and 
from  a large  acquaintance  with  other  similar  scale  pests  it  is  extremely 
improbable  that  even  under  the  most  favorable  circumstances  will  such 
natural  enemies  reduce  this  scale  as  much  as  would  one  thoro  treatment 
with  the  lime-sulfur  wash  or  other  standard  remedy.  The  insect 
enemy  of  the  scale  can  only  exist  when  it  has  scale  food;  hence  a nor- 
mal balance  is  very  soon  reached  in  which  the  scale  and  natuial  enem^ 
fluctuate  in  relative  abundance.  A complete  extermination  of  the 
scale  insect  or  host  will  rarely  if  ever  be  accomplished,  and  theie  will 
probably  always  be  enough  scale  present  to  cause  spotted  and  unmar k- 
etable  fruit.  This  does  not  mean  that  such  enemies  are  not  going  to 
be  helpful.  They  will  decrease  the  virulence  and  destructiveness  of 
the  scale,  but  to  get  clean  fruit  it  will  probably  be  always  necessary 
to  spray.  A very  few  scale  on  a tree  will  cause  spotted  fruit  even 
when  they  may  not  be  abundant  enough  to  do  the  tree  itself  material 
injury.  The  fact  that  a large,  succulent  scale  insect  like  the  fluted 
scale  of  California  has  been  controlled  by  a ladybird  enemy  does  not 
necessarily  allow  one  to  hope  for  the  same  result  with  the  San  Jose 
scale.  The  ladybird  and  other  enemies  introduced  into  California  to 
control  scales  similar  to  the  San  Jose  scale  have  not  succeeded  in  the 
same  measure  at  all.  This  statement  is  made  to  correct  hopes  which 
may  be  aroused  by  certain  popular  articles  which  have  recently 
appeared  on  the  subject  of  parasites. 

In  brief,  therefore,  the  San  Jose  scale  must  be  recognized  as  a per- 
manent condition  to  be  met  in  the  growth  of  deciduous  fruits.  The 
greatest  cafe  should  always  be  taken  in  the  purchase  of  nursery  stock 
to  see  that  it  is  absolutely  free  from  infestation,  and  preferably  also 
that  it  carries  with  it  a certificate  of  fumigation.  Orchards  should  be 
sprayed  according  to  well-established  methods  annually  as  soon  as  the 


10 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


first  sign  of  infestation  is  found.  Fruit  growers  and  others  interest© 
have  come  to  accept  this  conclusion  and  are  facing  the  San  Jose  seal 
problem  as  one  to  be  regularly  dealt  with,  as  with  other  establishe 
insect  enemies  of  fruits.  The  range  of  food  plants  of  this  scale  is  s 
great  that  local  extermination  is  out  of  the  question,  and  it  is  reco^ 
nized  as  useless  to  destroy  orchards  or  new  stock  because  of  sligb 
infestation.  The  San  Jose  scale  will  have  so  soon  gained  foothold  o 
many  ornamental  and  wild  plants  that  such  destruction  of  orchard 
would  be  of  no  avail,  and  new  stock  would  be  very  quickly  reinfeste 
from  near-by  sources. 

ORIGIN  OF  THE  INSECT. 

The  San  Jose  scale  was  first  established  in  this  country  in  the  earb 
seventies  at  San  Jose,  Cal.,  in  the  grounds  of  Mr.  James  Lick. 

Following  the  studies  of  Professor  Comstock  of  this  pest  in  Cali 
forma  in  1880,  efforts  have  been  made  to  determine  whence  the  origina 
infestation  came;  in  other  words,  to  locate  the  native  home  of  thi 
insect.  The  importance  of  discovering  the  origin  of  this  scale  arise; 
from  the  now  well-known  fact  that  .where  an  insect  is  native  it  is  nor 
mall}  kept  in  check  and  prevented  from  assuming  an}7  very  destructiv< 
features,  or  at  least  maintaining  such  conditions  over  a very  long  time 
by  natural  enemies,  either  parasitic  or  predaceous  insects  or  fungou: 
01  other  diseases.  Mr.  Lick,  in  whose  orchard  the  scale  first  appeared 
was  a great  lover  of  plants,  and  imported  trees  and  shrubs  for  the 
ornamentation  of  his  grounds  from  foreign  countries,  and  it  was  verJ 
naturally  inferred  that  in  some  of  these  importations  he  had  intro 
duced  this  insect.  Before  this  investigation  started,  however,  Mr. 
Lick  had  died,  and  it  was  impossible  to  trace  his  importations.  ? That! 
the  scale  was  not  European  in  origin  was  evident;  otherwise  it  woulJ 
undoubtedly  have  come  to  this  country  long  before  with  the  numeroul 
importations  of  stock  from  Europe.  Its  original  home  was  therefore! 
naturally  placed  in  some  eastern  country.  In  the  course  of  the  invesl 
tigation  it  was  found  that  the  San  Jose  scale  occurred  in  the  Hawaiian}] 
Islands,  in  Chile,  in  Japan,  and  in  Australia. a In  the  case  of  the! I 
Hawaiian  Islands  it  was  conclusively  shown,  however,  that  it  had  been}] 
carried  there  on  stock  from  California.  The  evidence  relating  to  Chile! J 
and  Australia  was  of  a similar  nature— namely,  that  it  had  come  td 
those  countries  comparatively  recently  on  imported  stock.  Its  occur- 
rence in  Japan  was  not  discovered  until  1897,  and  the  evidence  was  far 
from  being  conclusive  that  it  was  indigenous  in  that  country;  never- 
theless the  belief  that  Japan  was  the  source  of  this  scale  came  to  be 
rather  generally  accepted.  The  objections  to  it  were  voiced  by  Doctor 
Howard  and  the  writer  in  an  article  read  before  the  Association  of 

«See  Bui.  No.  3,  new  series,  Div.  Ent.,  U.  S.  Dept.  Agric.,  pp.  10-12,  1896. 


EXPLORATIONS  IN  JAPAN. 


11 


Economic  Entomologists  in  1899, a showing  that  at  best  the  evidence 
I 3ft  the  question  open.  That  this  scale  insect  probably  had  its  original 
, lome  in  China  or  Japan  seemed,  however,  to  be  prett}-  conclusively 
, ndicated  by  the  process  of  exclusion  of  other  countries.^  Mr. 
f Coebele’s  investigations  of  the  Asiatic  tropical  regions  and  Australia 
i jid  New  Zealand  had  been  fairly  thoro,  yet  without  finding  it  on  native 
dants,  and,  furthermore,  it  was  not  known  to  occur  in  South  Africa. 

I The  evidence  pointing  toward  Japan  and  China  was  further  empha- 
sized by  the  fact  that  the  San  Jose  scale  is,  by  its  relationship  and  dis- 
tribution, an  inject  of  the  temperate  regions  rather  than  of  the  Tropics. 

EXPLORATIONS  IN  EASTERN  ASIA. 

With  the  hope  of  settling  the  disputed  point  of  the  origin  of  the 
San  Jose  scale,  and,  if  the  native  home  of  the  species  were  discovered, 
to  study,  collect,  and  import  beneficial  insects  to  control  this  pest  in 
America,  the  writer,  in  1901-2,  made  a trip  of  exploration  in  Japan, 
(China,  and  other  Eastern  countries,  lasting  over  a year.  The  accom- 
panying  map  (PL  II)  illustrates  the  regions  explored.  Six  months 
were  devoted  to  a very  thoro  exploration  of  the  different  islands  of 
the  Japanese  Empire,  and  three  months  to  China,  with  shorter  periods 
in  other  regions.  The  explorations  in  China  and  Japan  are  the  only 
ones  which  bear  especially  on  the  San  Jose  scale  problem. 

EXPLORATIONS  IN  JAPAN. 

During  the  time  spent  in  Japan,  from  April  to  September,  1901, 
the  writer  visited  some  forty-two  provinces,  and  explored  all  the  prin- 
cipal islands,  representing  a stretch  in  latitude  the  equivalent  of  from 
northern  Maine  to  Florida.  Altogether  these  explorations  enabled 
him  to  make  a pretty  correct  judgment  on  the  San  Jose  scale  problem 
in  Japan.  Japan  is  not  especially  a horticultural  country.  Her  com- 
paratively enormous  population  of  46,000,000  compels  the  growth  of 
cereals  and  other  necessities  of  life  wherever  possible.  Very  little 
land,  therefore,  is  devoted  to  fruit  raising,  and  fruits  are  considered 
as  luxuries.  Nevertheless,  practically  every  dwelling  house  in  Japan 
has  a little  dooryard  or  kitchen  garden  in  which  are  single  examples 
of  cherry,  plum,  peach,  persimmon,  and  other  trees.  Furthermore, 
the  roadways  and  temple  grounds  and  streets  are  lined  with  cherry 
and  plum  trees,  planted  for  bloom  and  ornament  and  not  for  fruit. 
There  are  orchard  districts  in  Japan  of  limited  extent.  In  northern 
and  central  Japan  there  are  a few  peach  orchards  and  a few  orchards 
of  native  pears,  and  in  southern  Japan  small  orchards  of  orange, 
pomelo,  walnut,  and  other  fruits.  In  old  Japan  the  chief  deciduous 
fruit  is  a native  pear  grown  in  small  patches  of  from  a fraction  of  an 


«See  Bui.  No.  20,  new  series,  Div.  Ent.,  U.  S.  Dept.  Agric.,  pp.  36-39,  1899. 


12 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


acre  to  2 or  3 acres  in  extent.  These  are  trained  low  on  over- 
head trellises  (PI.  Ill),  and  at  a short  distance  look  like  vineyards. 
There  are  several  districts  where  such  orchards  occur  in  considerable 
numbers.  These  orchards  are  very  ancient,  many  of  them  having 
trees  more  than  one  hundred  years  old.  If  the  San  Jose  scale  were 
native  to  Japan  it  would  occur  in  these  pear  orchards,  the  pear  being 
one  of  the  favorite  food  plants  of  this  scale  insect. 

In  northern  Japan,  including  the  island  of  Hokkaido,  and  the  northern 
end  of  the  main  island,  Hondo,  apple  raising  has  been  introduced  in 
modern  times  very  much  on  the  lines  followed  in  this  country.  Prior 
to  the  opening  of  Japan  to  foreign  commerce  and  exploration  the 
apple  as  an  edible  fruit  was  unknown  in  that  country.  The  orchards 
in  northern  Japan  are  chief!  }7,  therefore,  of  American  origin  and  rep- 
resent American  varieties.  Most  of  the  stock  came  from  California, 
and  much  of  it  was  undoubtedly  infested  with  San  Jose  scale  when  it 
was  received.  There  is,  therefore,  thruout  these  northern  apple 
orchards  a mild  infestation  with  this  scale.  The  Japanese  are  ver}7 
enthusiastic  in  their  efforts  to  gain  all  the  benefits  of  western  civiliza-l 
tion,  and  this  is  shown  in  horticultural  as  well  as  in  other  fields.  The 
three  leading  nurseries,  therefore,  of  Japan  have  been  very  active  dur- 
ing the  last  twenty  or  thirty  years  in  importing  the  different  varieties 
of  pear,  peach,  and  apple  from  America,  and  all  three  of  these  nursery 
districts  have  become  infested  Avith  San  Jose  scale,  evidently  from  such 
importations  from  California,  where  the  scale  has  been  widely  dis- 
tributed for  thirty  years.  Outside  these  nurseries,  however,  in  cen- 
tral and  southern  Japan,  the  San  Jose  scale  did  not  occur,  except  where 
it  had  been  introduced  on  new  stock  from  the  nurseries  referred  to. 
The  old  native  pear  orchards  were  free  from  scale,  except  where 
replants  had  been  made  of  American  varieties,  or  new  native  stock,  to 
fill  in  breaks  in  the  orchards.  The  infestation  was  very  often  just 
beginning  and  immediately  surrounded  the  replants.  In  all  Japan, 
therefore,  in  the  little  house  gardens  and  temple  grounds  where  were 
cherry,  plum,  and  other  trees  suitable  for  San  Jose  scale,  this  insect 
did  not  occur,  except  where  the  evidence  was  very  plain  of  its  recent 
introduction  as  indicated.  Without  going  into  details  of  the  evidence, 
it  is  sufficient  to  say  that  the  conditions  in  Japan  are  essentially  the 
same  as  in  this  country.  The  San  Jose  scale  is  a recent  comer.  It 
was,  in  fact,  not  known  in  Japan  prior  to  the  year  1897,  when  its 
presence  there  was  first  determined,  but  it  has  now  been  scattered 
pretty  widely  by  nursery  stock,  exactly  as  in  this  country,  and  occurs j 
under  similar  conditions;  in  other  words,  only  where  it  has  been 
recently  introduced.  The  investigation  showed  very  distinctly  that 
Japan  could  not  be  considered  responsible  for  the  San  Jose~scale. 

The  results  and  conclusions  arrived  at  by  the  writer  were  after- 
wards fully  confirmed  by  a very  thoro  and  painstaking  explora- 


Bui.  62,  Bureau  of  Entomology,  U.  S.  Dept,  of  Agriculture. 


Plate  III. 


Fig.  1.— Japanese  Apple  Orchard,  Showing  Trellis  Method  of  Training. 
(Author’s  Illustration. ' 


Fig.  2.— Old  Native  Pear  Orchard  of  Japan,  Showing  Method  of  Training. 
'Author’s  Illustration. i 


LIBRARY 

UNIVERSITY  OF  ILLINOIS 
URBANA 


EXPLORATIONS  IN  CHINA. 


13 


ion  of  the  entire  Japanese  Empire  conducted  by  Japanese  entomolo- 
f fists  under  the  authority  of  the  Imperial  Agricultural  Experiment 
; station  in  Japan.  The  publication  giving  the  results  of  this  investiga- 
\ona  is  a very  interesting  and  valuable  contribution  to  our  knowledge 
)f  the  subject,  and  is  illustrated  by  numerous  maps  and  figures. 

EXPLORATIONS  IN  CHINA. 

Investigations  up  to  this  point,  while  freeing  Japan  from  the  onus 
)f  giving  the  San  Jose  scale  to  the  world,  left  the  problem  unsettled 
is  to  the  original  home  of  this  insect.  China  remained  as  the  most 
likely  place  of  origin,  and  the  writer  proceeded  to  China  to  continue 
his  explorations  there.  While  in  Japan  a good  deal  of  information 
was  gained  relative  to  fruit  conditions  in  China,  from  English,  Ger- 
man, and  American  residents  who  were  spending  the  summer  months 
in  Japan  to  escape  the  rather  trying  climate  of  China.  In  brief,  it 
may  be  stated  that  deciduous  fruits  are  grown  from  the  Shanghai 
region  northward,  the  peach  being  practically  the  only  fruit  grown  to 
any  extent  about  Shanghai.  The  great  apple  district  of  China  is  the 
region  lying  back  of  the  city  of  Chifu  in  the  north.  This  apple- 
growing industiy  was  started  many  years  ago  by  a missionary,  Doctor 
Nevius,  and  has  assumed  very  considerable  proportions  and  covers  a 
good  deal  of  the  province  of  Shantung.  Below  Shanghai  the  orange 
and  other  subtropical  fruits  replace  the  deciduous  varieties.  North 
of  Chifu  native  fruits  only  are  grown,  consisting  of  the  native  pear 
and  peach,  and  such  wild  fruits  as  wild  crab  apples  and  an  edible  haw 
apple. 

A very  considerable  exploration  of  the  country  lying  immediately 
back  of  Shanghai  was  made  in  the  course  of  a long  house-boat  trip.  A 
great  man}7  peach  orchards  were  examined  and  a good  deal  of  mis- 
cellaneous fruit  and  other  plants  growing  about  house  yards  were 
inspected.  Nowhere  was  there  any  evidence  of  the  San  Jose  scale, 
nor  were  scale  insects  of  any  sort  much  to  be  seen.  The  climate  of 
this  region  is  unfavorable  for  such  insects  and  they  are  normally 
killed  out  by  fungous  disease.  The  writer  afterwards  proceeded  by 
boat  to  Chifu — a five-day  ocean  trip  from  Shanghai,  and  made  a con- 
siderable exploration  thruout  the  apple  orchards  of  this  region  on 
horseback,  visiting,  among  others,  the  original  orchards  planted  by 
Doctor  Nevius.  In  all  these  the  San  Jose  scale  was  found  scatteringly 
present,  not,  however,  doing  any  special  damage,  and  probably  not 
enough  to  be  noticed,  if  its  possibility  for  evil  was  not  so  well  estab- 
lished. The  presence  of  the  San  Jose  scale  in  this  region  did  not, 
however,  have  any  special  significance,  since  much  of  the  original 

“The  San  Jose  scale  in  Japan.  Imperial  Agricultural  Experiment  Station,  Tokyo, 

1904. 


14 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


stock  was  obtained  from  California,  and  doubtless  from  nurseries 
which  were  infested  with  the  scale. 

The  journey  of  exploration  was  continued  northward  to  Tientsin  and 
Pekin.  In  this  region  the  San  Jose  scale  was  found  on  native  plants 
also,  including  the  flowering  peach,  a tree  grown  for  ornament  solely, 
and  not  for  fruit,  and  notably  on  the  native  fruits  in  the  markets  in 
these  cities. 

The  markets  of  Pekin  were  of  especial  interest  in  this  connection. 
Pekin  is  the  center  and  market  for  all  the  region  lying  to  the  north 
and  west,  and  the  streets  (PI.  IV,  tig.  2)  devoted  to  the  sale  of  fruits 
and  other  products  in  the  Chinese  city  are  pne  of  the  great  show 
places.  The  fruit  and  nut  products  are  brought  into  Pekin  in  little 
two-wheeled  carts  (PI.  IV,  fig.  1),  or  more  generalty  on  camelback, 
great  caravans  of  heavily  loaded  camels  and  streams  of  carts  constantly 
entering  the  cityT  with  the  products  of  the  outtying  provinces.  One 
finds,  therefore,  in  the  markets  of  the  Chinese  cit}T  the  fruit  products 
of  all  northern  China,  and  can  stud}r  them  at  ease.  All  the  district 
tying  between  Pekin  and  the  great  wall,  north  and  west  and  east,  has 
been  most  carefully  explored  and  mapped  by  the  foreign  military 
authorities.  From  various  individuals  emptyyed  in  this  minute  sur- 
vey a great  deal  was  learned  relative  to  the  fruit  growing  in  the  dis- 
trict indicated.  Much  of  the  fruit  found  in  the  markets  of  Pekin 
comes  from  the  hill  region  leading  up  to  the  mountains  separating 
China  from  Mongolia  and  Manchuria.  These  fruits  are  native  apples, 
pears,  and  peaches,  and  the  little  haw  apple  already  mentioned.  Great 
quantities  of  these  fruits  were  examined  in  the  market,  with  the  excep- 
tion of  the  peach,  which  was  then  out  of  season,  and  later  similar 
examinations  were  made  at  Tientsin.  A very  scanty  but  general  infes- 
tation with  San  Jose  scale  was  found  on  the  different  fruits  examined. 
Perhaps  one  apple  in  a hundred  would  have  a few  of  these  scales  about 
the  blossom  end  and  the  same  proportion  was  true  of  the  haw  apple 
and  the  native  pear.  Thruout  the  region  where  these  fruits  are  grown 
there  has  been  no  introduction  of  foreign  stock.  The  occurrence  of  the 
San  Jose  scale  on  these  two  fruits  was  conclusive  evidence  that  in  the 
region  whence  they  came  the  San  Jose  scale  is  native.  The  scattering 
occurrence  of  the  scale  also  indicated,  as  would  be  anticipated,  that 
this  pest  in  its  native  home  is  kept  in  check  by  natural  means. 

The  investigations  made  at  Shanghai,  and  later  southward  to  Hong- 
kong, the  Mala}r  Peninsula,  and  Java,  indicated  that  the  San  Jose 
scale  in  eastern  Asia  can  not  survive  below  Shanghai. 

The  sp  cial  distii  t where  it  is  native  and  thrives  is  a fairty  well 
shut-off  region,  which  probably  accounts  for  the  failure  of  this  insect 
to  beco  i e a world  pest  ages  ago.  This  district  is  the  region  leading 
up  to  the  mountains  and  comprising  the  northern  and  northeastern 


Bui.  62,  Bureau  of  Entomology.  U.  S.  Dept,  of  Agriculture. 


Plate  IV. 


Pg.  1.— Pony  Fruit  Cart  in  which  Products  of  the  Hill  Country  are  Brought 
into  Pekin,  China.  Author’s  Illustration.) 


Fig.  2.— Portion  of  Street  Devoted  to  Sale  of  Fruits  in  Pekin,  China. 
(Author’s  Illustration.  ) 

[In  foreground,  fruit  samples;  in  background,  storehouses,  also  dromedaries  employed  to  bring 
products  from  remote  provinces.] 


LIBRARY 

university  of  Illinois 

URBANA 


HISTORY  IN  CALIFORNIA  AND  THE  WEST. 


15 


frontiers  of  China  proper.  Beyond  the  great  wall  on  the  north  and 
west  lies  Mongolia,  consisting  chiefly  of  the  vast  Desert  of  Gobi.  To 
the  northeast,  and  separating  the  region  from  Manchuria  and  Korea, 
is  the  eastern  Gobi  Desert.  To  the  south  and  east  lies  the  great  alluvial 
plain,  the  product  of  centuries  oh  mud  carried  down  by  the  Yellow 
River,  a region  where  cereals  only  are  grown.  These  are  all  effective 
barriers,  and  especially  so  when  considered  in  connection  with  the 
political  conditions  of  the  past.  We  have,  therefore,  as  the  original 
home  of  this  insect  a naturally  shut-off  area  from  which  it  could  not 
easily  escape  under  the  conditions  prevailing  up  to  our  own  times. 

The  means  by  which  the  San  dose  scale  came  from  China  to  America 
is  a matter  of  interest.  As  previously  stated,  it  is  believed  that  this 
pest  reached  California  on  trees  imported  by  the  late  James  Lick. 
It  is  the  writer’s  belief  that  Mr.  Lick  imported  from  China,  possibly 
thru  Doctor  Nevius,  with  whom  he  was  probably  in  correspondence,  the 
flowering  Chinese  peach,  and  brought  with  it  the  San  Jose  scale  to  his 
premises.  Undoubtedly  this  scale  insect  came  to  this  country  in  some 
such  way  on  ornamental  stock  from  China. 

RECORD  OF  THE  SPREAD  OF  THE  INSECT. 

No  attempt  will  be  made  to  trace  the  details  of  the  later  (extension 
of  the  San  Jose  scale,  but  the  earlier  history  of  this  scale  in  the 
United  States  is  well  worthy  of  record  as  is  also  a summary  at  least  of 
the  means  by  which  it  became  so  widely  and  disastrously  distributed 
so  shortly  after  its  first  appearance  on  the  Atlantic  side  of  the 
Continent. 

HISTORY  IN  CALIFORNIA  AND  THE  WEST. 

The  spread  of  the  San  Jose  scale  from  the  point  of  original  infesta- 
tion in  the  San  Jose  Valley  was  somewhat  rapid,  its  area  increasing  in 
every  direction,  but  more  rapidly  toward  the  north  and  the  west.  By 
1873  it  had  become  a serious  pest  in  orchards  which  had  direct  con- 
nection with  that  of  Mr.  Lick,  and  in  1880,  when  Professor  Comstock 
studied  it,  he  reported  that  he  had  never  seen  any  other  species  so 
abundant  and  injurious  as  this  was  in  certain  orchards.  As  reported 
by  Mr.  Coquillett,  it  had  extended  as  far  west  as  San  Francisco  by 
1883,  but  it  had  not  reached  important  deciduous-fruit  districts  in 
southern  California  three  years  later.  Prior  to  its  reaching  the  East 
in  1886  or  1887  it  had  slowly  extended  its  range  on  the  Pacific  coast 
and  in  States  west  of  the  Rocky  Mountains,  including  California, 
Oregon,  Washington,  and  Idaho  on  the  north,  and  Nevada,  Arizona, 
and  New  Mexico  on  the  south.  In  the  earty  nineties  it  had  penetrated 
into  British  Columbia. 


8449— No.  62—06 2 


16 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


HISTORY  IN  THE  EAST. 

The  general  records  of  the  discovery  of  the  insect  in  the  East  are 
reproduced,  with  slight  changes,  from  Bulletin  3. 

The  occurrence  of  the  San  Jose  scale  in  the  East  was  first  discovered  * 
early  in  August,  1893,  in  the  grounds  of  Dr.  C.  H.  Hedges,  of  Char- 
lottesville, Va.  An  infested  pear  had  been  sent  by  Doctor  Hedges  to  li 
Mr.  Gallo  way,  chief  of  the  Division  of  Vegetable  Physiology  and 
Pathology  of  the  Department  of  Agriculture,  on  the  supposition  that 
it  was  affected  by  a fungous  disease.  The  fruit  was  submitted  to  the 
then  acting  entomologist,  Doctor  Howard,  who  immediately  recognized 
the  injury  as  due  to  the  San  Jose  scale,  and  the  startling  and  deplor- 
able fact  was  established  of  the  introduction  into  eastern  orchards  of 
this  worst  scourge  of  deciduous  trees  of  the  Pacific  Slope,  as  well  as 
the  fact  that  it  was  evidently  able  to  maintain  itself  in  a supposedly 
less  favorable  climate.  The  importance  of  this  discovery  was  at  once 
realized,  and  two  agents  of  the  Bureau,  Messrs.  Schwarz  and  Coquil- 
lett,  were  detailed  to  make  a thoro  investigation.  In  conjunction  with 
the  State  board  of  agriculture  of  Virginia  and  under  the  supervision 
of  Mr.  Coquillett  a thoro  fumigation  with  hydrocyanic  acid  gas  was 
given  to  the  infested  trees  and  plants. 

The  introduction  of  the  scale  was  subsequently  traced  to  currant 
bushes  purchased  from  a New  Jersey  firm. 

In  March,  1891,  the  presence  of  the  scale  was  determined  by  Doctor 
Howard,  at  Riverside,  Charles  County,  Md.,  in  a rather  large  orchard 
situated  on  the  river  front,  and  including  over  two  thousand  peach 
and  several  hundred  apple  trees.  This  orchard  was  visited  by  the 
writer,  who  found  that  many  of  the  trees  were  infested  with  the  San 
Jose  scale,  large  numbers  having  already  perished.  The  infested  stock; 
was  again  in  this  instance  traced  to  a New  Jersey  nursery.  This 
orchard,  on  account  of  its  proximity  to  Washington  and  the  facilities 
thus  afforded  for  experiment,  was  used  by  the  Bureau  in  the  testing 
of  various  washes  for  this  scale. 

During  the  same  month  (March,  1891)  specimens  of  the  San  Jose 
scale  were  received  from  De  Funiak  Springs,  Fla.,  thru  the  ento- 
mologist of  the  Florida  Experiment  Station,  Mr.  P.  H.  Rolfs.  The; 
late  Mr.  H.  G.  Hubbard,  one  of  the  assistants  of  the  division,  visited 
the  infested  locality  and  found  the  scales  confined  chiefly  to  peach 
and  plum,  occurring,  however,  in  small  numbers  on  Kieffer  pear, 
pecan,  and  persimmon.  Many'  thousands  of  trees  were  found  to  be 
infested,  including  nearly  every  orchard  within  a radius  of  5 or  6 
miles.  The  source  of  the  infestation  in  this  case  was  not  definitely 
ascertained,  but  it  was  evident  after  examination  that  some  infested 
nursery  had  sent  a shipment  of  trees,  and  the  indications  were  that 


PRINCIPAL  SOURCES  OF  INFESTATION  IN  THE  EAST.  17 


there  had  been  repeated  importations,  the  first  indication  of  injury 
having  been  noted  six  years  before. 

On  receipt  of  the  Florida  specimens  Doctor  Howard  concluded  that 
as  the  scales  had  been  found  in  three  such  widely  separated  locali- 
ties, and  as  the  information  gained  from  the  owners  of  two  of  the 
affected  orchards  led  to  the  supposition  that  the  original  stock  had 
been  obtained  from  a large  eastern  nursery,  the  probabilities  were 
strong  that  the  scale  had  established  itself  in  many  eastern  points 
during  the  preceding  five  or  six  years.  He  therefore  immediately  pre- 
pared a circular  of  warning  and  had  nearly  12,000  copies  mailed  early 
in  April  to  all  eastern  agricultural  newspapers  and  to  very  many  eastern 
fruit  growers.  As  a result  of  the  issuing  of  this  circular  many  new 
localities  for  the  scale  were  ascertained,  a widespread  interest  in  the 
subject  was  aroused,  and  careful  investigations  were  made  in  all  the 
States  to  which  there  was  any  likelihood  that  the  insect  had  been 
carried  by  nursery  stock  or  other  means. 

By  the  end  of  August,  1894,  the  scale  was  known  to  occur  in  the 
following  localities  in  the  East:  In  a rather  widely  extended  district 
in  Florida,  one  locality  in  Virginia,  three  in  Maryland,  one  in  Indiana, 
two  in  Pennsylvania,  many  in  New  Jersey,  and  one  in  New  York,  on 
the  east  bank  of  the  Hudson  River  a little  below  Albany.  Very  shortly 
afterwards,  during  the  same  summer,  it  was  found  on  Long  Island, 
occurring  both  in  orchards  and  nurseries.  Later  in  the  fall  the  scale 
was  found  at  three  new  localities  in  Maryland,  and  still  later  specimens 
were  received  from  the  extreme  southern  part  of  Georgia.  In  Decem- 
ber Professor  Webster  reported  receiving  the  scale  from  a large 
orchard  district  in  southern  Ohio,  and  a little  later  specimens  were 
received  from  Jefferson  County,  Ind.  The  scale  was  found  also  near 
New  Castle,  Del.,  in  Januaiy,  1895,  and  additional  localities  were  dis- 
covered during  the  following  spring  and  summer  of  1895  in  some  of 
the  States  mentioned,  as  also  in  Alabama,  Louisiana,  and  Massachu- 
setts. In  nearly  every  instance  the  source  of  infestation  in  the  East 
was  the  same,  namely,  one  or  the  other  of  two  important  New  Jersey 
nurseries. 

PRINCIPAL  SOURCES  OF  INFESTATION  IN  THE  EAST. 

As  stated,  nearly  all  the  eastern  occurrences  of  the  San  Jose  scale 
were  traced  to  two  large  New  Jersey  nurseries,  from  which  infested 
stock  had  unwittingly  been  sent  out  broadcast  for  certainly  six  or  seven 
years.  The  damage  thus  done  to  the  fruit  interests  of  the  East  by 
these  nurserymen  can  hardly  be  estimated,  and  yet  it  must  be  admitted 
that  they  were,  in  a measure,  blameless,  since  they  were  undoubtedly 
entirely  unaware  of  the  dangerous  character  of  the  scale  insect  which 
infested  their  stock.  We  can  hardly  avoid  the  conclusion,  however, 


18 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


that  they  were  aware  that  they  were  distributing  diseased  stock,  since 
to  deny  this  presupposes  that  the  stock  received  no  examination.  If 
the  scale  was  noticed  it  was  doubtless  supposed  to  be  one  of  the  com- 
mon eastern  species,  which,  while  had  enough,  are  of  little  importance 
compared  with  the  San  Jose  scale. 

The  two  nurseries  responsible  for  the  original  eastern  introduction 
of  the  scale  became  infested  in  the  same  way.  Either  in  1886  or  1887, 
in  the  endeavor  to  secure  a thoroly  curculio-proof  plum,  both  of  these 
nurseries  introduced  from  California  an  improved  Japanese  variety, 
the  Kelsey,  obtained  from  the  San  Jose  district.  We  have  the  state- 
ment from  the  proprietors  of  one  of  the  nurseries  that  the  plum  trees 
in  question  , were  secured  in  the  spring  of  1887  from  San  Jose,  Cal., 
and  were  shipped  thru  the  agency  of  a Missouri  nursery  company,  which 
acted  in  this  instance  apparently  as  a mere  transmitting  agent.  ' The 
trees  were  unquestionably  thoroly  infested  when  received,  did  not 
thrive,  and  in  both  cases  most  of  them  were  ultimately  taken  out  and 
destroyed.  The  stock,  however,  had  been  multiplied  by  nursery 
methods,  and  from  the  original  stock,  and  that  subsequently  obtained, 
the  scale  spread  more  or  less  completely  thruout  both  of  the  nurseries 
in  question.  Both  of  these  firms,  when  the  nature  of  the  infestation 
was  brought  to  their  attention  and  the  seriousness  of  the  damage  they 
were  doing  was  made  apparent  to  them,  undertook  measures  to 
exterminate  the  scale. 

In  addition  to  the  two  prominent  nurseries  mentioned,  several  smaller 
nurseries  in  the  East  were  found  to  harbor  this  scale.  Some  of  these 
had  been  recently  infested,  but  in  others  the  infestation  was  of  long 
standing.  Three  nurseries  of  the  latter  class  were  located  on  Long 
Island,  and  apparently  received  their  original  scales  from  New  Jersey; 
one  in  Florida,  reported  by  Prof.  P.  H.  Rolfs,  and  two  in  Georgia 
apparent^  received  infested  stock  from  eastern  sources,  and  one  or 
more  each  in  Louisiana,  Mississippi,  and  Alabama  became  infested 
with  the  scale  thru  pear  stock  coming  from  Lewiston,  Idaho.  In  Mas- 
sachusetts there  were  infested  nurseries  at  Cambridge  and  Bedford, 
the  origin  of  the  scale  in  these  cases  being  obscure;  and  a nursery  in! 
Missouri  was  under  suspicion  as  having  been  the  agency  thru  which 
the  original  infested  Japanese  plums  were  transmitted  to  eastern* 
nurseries.  Two  infested  nurseries  were  known  to  exist  in  Maryland; 
also. 

SUMMARY,  BY  STATES  AND  TERRITORIES,  OF  DISTRIBUTION 
AND  PRESENT  CONDITION. 

The  detailed  facts  relating  to  the  first  introduction  of  the  San  Jose| 
scale  into  the  several  States  are  given  in  Bulletins  3 and  12,  and  with 
greater  minuteness  in  the  various  publications  of  the  experiment  sta- 
tions of  the  several  States  involved.  The  distribution  has  now  become 


SUMMARY  OF  DISTRIBUTION  AND  PRESENT  CONDITION.  19 

io  general  in  most  of  the  States  where  the  San  Jose  scale  has  occurred 
for  a number  of  years  that  it  is  impracticable  to  indicate  the  different 
points  of  infestation,  and  even  in  the  States  worst  infested  many 
orchards  are  free  from  the  scale;  but  if  an  attempt  was  made  to  graph- 
ically picture  the  distribution  on  a map,  the  points  of  infestation 
would  be  so  numerous  as  to  give  the  appearance  of  absolutely  complete 
infestation.  The  publications  cited  may  be  referred  to,  therefore, 
for  the  more  detailed  and  complete  records.  A mere  statement  of  the 
present  general  status  of  the  San  Jose  scale  in  the  several  States  in 
which  it  occurs  will  now  be  given.  This  statement  is  based  on  replies 
to  a circular  letter  of  inquiry  sent  to  State  entomologists  and  experi- 
ment station  officers  in  May  of  this  year. 


Fig.  1. — Map  of  the  United  States,  showing  localities  known  to  have  been  infested  with  the  San  Jose 

scale  up  to  1896.  (Original.) 


It  is  interesting  for  comparison  to  reproduce  the  map  (fig.  1)  show- 
ing the  known  distribution  at  the  time  of  the  publication  of  Bulletin  3 
in  1896,  when  the  scale  was  reported  in  only  20  States  and  in  compara- 
tively few  localities  in  each,  with  the  single  exception  of  New  Jersey, 
which  had  been  most  energetically  inspected  by  Dr.  John  B.  Smith 
and  found  to  be  very^  generally  infested.  Bulletin  12  records  the  scale 
occurring  in  33  States  and  also  in  the  District  of  Columbia  and  Canada, 
and  in  very  many  new  localities  in  all  of  the  States  previously  recorded 
as  harboring  the  scale.  The-  number  of  actual  records  of  the  San 
Jose  scale  now  available  are  many  hundredfold  what  they  were  at  the 
time  of  the  publication  of  Bulletin  12  at  the  beginning  of  the  year 
1898. 

There  are  still  a few  States  in  which  the  San  Jose  scale  does  not 
now  occur  or  has  not  been  reported,  namely,  Colorado,  Maine,  Minne- 


20 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


sota,  Nebraska,  North  and  South  Dakota,  Wisconsin,  and  Wyoming] 
It  probably  occurs  in  some  of  these  States,  however,  altho  it  has  so 
far  escaped  notice.  . 

ALABAMA. 


The  occurrence  of  the  San  .lose  scale  in  Alabama  was  first  indicated 
in  April,  1885,  by  material  received  from  Prof.  J.  W.  Hoffman,  of 
the  Tuskegee  Institute,  Tuskegee.  As  now  reported  by  Mr.  R.  S. 
Mackintosh,  State  horticulturist,  the  infestation  is  scattering  thruout 
the  State,  but  chiefty  along  some  of  the  main  railroad  lines,  and  most 
of  the  infested  orchards  became  so  before  people  knew  about  the 
scale  and  before  the  adoption  of  quarantine  measures  to  prevent  its 
introduction  and  spread. 

ARIZONA. 

The  San  Jose  scale  has  been  present  in  Arizona  in  the  older  orchards 
of  the  Salt  River  Valley  for  more  than  twent}T  years.  Director  R.  II. 
Forbes,  of  the  agricultural  experiment  station,  now  reports  that  this 
scale  insect  has  rather  dropt  out  of  sight,  probably  because  of  the 
succession  of  excessively  hot  dry  years  from  1899  to  1901,  inclusive. 
During  this  period  a large  proportion  of  the  deciduous  fruit  trees, 
including  almonds,  peaches,  pears,  apricots,  and  apples,  perished, 
apparently  from  lack  of  irrigating  water  and  partU  from  the  effect  of 
extremely  high  temperature  and  dryness. 

ARKANSAS. 

The  presence  of  the  San  Jose  scale  in  this  State  is  recorded  in  Bul- 
letin 12  (1898),  on  material  reported  by  Professor  Stinson.  Mr.  C.  F. 
Adams,  the  entomologist  of  the  agricultural  experiment  station,  now 
states  that  the  spread  of  this  insect  is  still  not  very  general;  that  it 
has  been  reported  from  several  counties,  and  that  he  has  seen  it  in  two 
florists’  establishments,  but  has  not  found  it  in  any  of  his  nursery 
inspection. 

CALIFORNIA. 

The  San  Jose  scale  has,  of  course,  long  been  generally  disseminated 
thruout  the  State.  Prof.  C.  W.  Woodworth,  entomologist  of  the 
agricultural  experiment  station,  now  reports  that  it  does  not  occur  at 
Berkeley,  but  probably  occurs  everywhere  else  in  the  State  where  fruit 
trees  are  grown,  except  in  isolated  plantings  in  the  foothill  regions. 
Usually  it  is  not  seriously  troublesome,  tho  it  may  increase  rapidty  at 
any  time  and  become  a pest.  The  uniform  treatment  with  the  lime, 
sulfur,  and  salt  wash  keeps  it  in  check,  and  parasitism  is  often  fairly 
efficient.  In  some  districts,  as  about  San  Jose,  where  it  has  almost 
disappeared,  the  result  may  be  due  both  to  parasitism  and  to  some 


SUMMARY  OF  DISTRIBUTION  AND  PRESENT  CONDITION.  21 


obscure  form  of  disease  as  well  as  to  the  lime-sulfur  treatment.  In 
southern  California  it  is  particularly  troublesome  in  apple  orchards. 
The  principal  variety  of  apple  grown  is  the  White  Pearmain,  and  the 
comparatively  rough  bark  of  this  variety  makes  it  difficult  to  get  very 
satisfactory  results  from  the  lime-sulfur  wash.  The  varieties  of  apple 
commonly  grown  in  northern  California — for  example,  Newton  Pippin 
and  Yellow  Bellflower — are  smooth  barked,  and  better  results  with  the 
wash  are  gained.  Taking  the  State  as  a whole,  Professor  Woodworth 
says  that  it  will  be  readily  found  in  at  least  25  per  cent  of  the  or- 
chards, in  injurious  numbers  in  probably  10  percent  in  an}^  one  year, 
and  that  from  25  per  cent  to  40  per  cent  of  the  orchards  are  sprayed 
with  the  lime,  sulfur,  and  salt  wash  every  year. 

COLORADO. 

The  San  Jose  scale  has  apparently  not  yet  obtained  foothold  in 
Colorado,  but  it  has  been  sent  to  us  from  Colorado  on  fruit  imported 
from  California.  The  probable  explanation  is  that  the  fruit  regions 
of  Colorado  are  above  the  climatic  range  of  this  scale  insect. 

CONNECTICUT. 

The  San  Jose  scale  is  recorded  for  at  least  five  localities  in  Bulletin 
12.  The  increase  of  this  scale  in  Connecticut  has  been  pretty  rapid, 
and  Mr.  W.  E.  Britton,  State  entomologist,  expresses  the  belief  that 
there  is  now  no  town  in  the  State  which  is  not  infested,  tho  he  may 
not  have  records  from  quite  all  of  the  towns.  It  is  found  very  gen- 
erally, at  any  rate,  in  all  of  the  larger  cities,  which  are  thoroly 
infested.  Practically  all  of  the  larger  orchards  are  infested,  tho  per- 
haps only  slightly".  He  says  that  there  are  many  orchards  and  trees 
which  are  still  exempt,  but  that  there  is  no  general  region  of  the  State 
where  the  scale  can  not  be  found. 

DELAWARE. 

Delaware,  as  recorded  in  Bulletins  3 and  12,  became  generally 
infested  very  early.  Mr.  Wesley  Webb,  secretary  of  the  State  board 
of  agriculture,  now  informs  us  that  the  San  Jose  scale  occurs  in  all 
parts  of  Newcastle  County  and  in  approximately  one-half  of  the 
orchards.  In  Kent  County  there  are  many  young  peach  orchards, 
and  more  than  one- hi ' 11  f of  .bn  are  infested  to  a greater  or  less  extent, 

a large  proportion  of  them,  however,  only  slightly  so.  In  the  western 
half  of  Sussex  County,  along  the  railroad  from  Farmington  to  Delmar, 
nearly  half  of  the  orchards  are  somewhat  infested,  while  in  the  east- 
ern half  of  the  county  from  Lincoln  southward  there  are  but  few 
orchards,  and  these  are  comparatively  free  from  scale. 


22 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


DISTRICT  OF  COLUMBIA. 

The  occurrence  of  the  San  Jose  scale  in  the  District  is  reported  in 
Bulletin  12,  and  it  is  now  pretty  generally  distributed  on  fruit  trees 
in  the  city  of  Washington  and  its  suburbs. 

FLORIDA. 

The  occurrence  of  the  San  Jose  scale  in  Florida  was  brought  to  our 
attention  in  March,  1894,  as  recorded  in  Bulletin  3,  and  additional 
localities  soon  followed.  Mr.  E.  W.  Berger,  assistant  entomologist 
of  the  State  experiment  station,  reports  that  the  present  distribution 
is  extensive,  the  scale  occurring  in  some  twenty-odd  counties^  or 
wherever  peaches  are  grown. 

GEORGIA. 

The  early  records  of  Georgia  infestation  beginning  in  1894  are 
given  in  Bulletins  3 and  12.  The  San  Jose  scale  in  1894  had  a pretty 
strong  foothold  in  this  State.  The  recent  conditions  in  Georgia  are 
indicated  on  a map  prepared  hy  Mr.  Newell  and  published  in  the  pro- 
ceedings of  the  Twenty-eighth  Annual  Meeting  of  the  Georgia  State 
Horticultural  Society,  in  1904.  This  map  indicates  very  general  I 
infestation  thruout  the  State,  including  most  of  the  counties  where  I 
fruit  growing  is  of  any  importance.  Prof.  Hugh  N.  Starnes,  in  a i 
letter  transmitting  this  report,  states  that  the  large  increase  indicated 
on  this  map  does  not  mean  that  infestation  is  still  progressing,  but  I 
merely  that  it  has  been  more  definitely  located  and  the  present  State  | 
laws  looking  to  the  control  of  this  pest  are  ample  in  their  provisions  and 
are  being  rigorously  enforced.  Mr.  Newell  reports  in  this  connection 
that  during  1904  out  of  a total  of  218  nurseries  inspected,  only  9 were 
found  infested,  and  that  this  is  a very  considerable  reduction  from  the  1 
percentage  of  infestation  shown  by  records  of  previous  years. 

IDAHO. 

The  infestation  in  this  State  is  directly  from  western  sources  and  is 
of  long  standing,  at  least  in  the  limited  area  about  Lewiston,  where 
the  oldest  orchards  are  located.  Mr.  L.  F.  Henderson,  the  entomolo-  I 
gist  of  the  State  experiment  station,  reports  on  the  present  situation  i 
under  date  of  May  29  as  follows: 

.s  in 

The  scale  is  very  prevalent  along  the  lower  river  bottoms,  such  as  Lewiston  on  I 
Clearwater,  Juliaetta  and  Kendrick  on  Potlatch  River  (a  tributary  to  Clearwater),  i 
up  and  down  the  Snake  at  Weiser,  Payette,  Caldwell,  Nampa,  as  far  as  Glenns  Ferry, 
possibly  farther.  Its  eastern  limit  seems  about  Mountain  Home,  as  I do  not  know  of  - 
it  at  Shoshone.  It  does  [not?]  exist  on  the  upper  Snake,  as  Blackfoot,  nor  in  the 
extreme  southeast,  as  Montpelier.  The  elevation  of  this  district  seems  too  high  for  it. 
as  it  varies  from  4,000  to  7,000  feet  altitude.  The  altitude  seems  also  too  high  about 


Summary  of  distribution  and  present  condition. 


23 


Iosco w and  Rathdrum,  tho  this  altitude  (2,500  feet)  is  not  more  than  at  Weiser  and 
toise.  Possibly  greater  rainfall  in  these  last  districts  discourages  it.  At  any  rate, 
vrhile  it  has  existed  at  Lewiston  for  fifteen  years,  it  has  not  ascended  to  Genesee,  12 
uiles  distant,  but  nearly  1,800  feet  higher. 

In  many  places  it  is  being  well  controlled  in  the  orchards,  where  careful  and  sys- 
ematic  spraying  with  lime-sulfur  spray  is  done. 

ILLINOIS. 


- The  San  Jose  scale  was  located  in  Illinois  in  1896  by  Professor 
Forbes,  who,  at  the  end  of  the  following  year,  had  found  the  scale  in 
22  colonies  in  11  counties,  as  reported  in  Bulletin  12  of  this  Bureau. 
In  a recent  letter  Professor  Forbes  gives  the  details  of  the  present 
infestation,  which  may  be  briefly  summarized  as  follows:  One-half  of 
the  counties  (51  of  the  102)  of  the  State  are  now  known  to  be  more  or 
less  infested,  but  43  per  cent  of  the  infested  orchards  are  included  in 
2 of  these  counties  and  80  per  cent  in  5 counties,  and  in  30  of  the 
counties  listed  the  average  number  of  infested  orchards  is  but  3^. 
In  four  of  the  counties  the  infestation  is  found  only  in  one  or  more 
towns  and  not  in  orchards.  It  will  be  seen  from  this  statement  that 
while  the  San  Jose  scale  is  pretty  widely  scattered  thruout  the  State, 
as  it  is  also  in  adjoining  States,  it  is  far  from  having  gained  a gen- 
eral foothold  save  in  a few  counties,  and  even  in  the  worst  counties 
infestation  is  not  yet  general.  In  no  States  has  inspection  and  reme- 
dial work  been  carried  out  more  thoroty  than  in  Illinois,  and  this 
accounts  for  the  rather  favorable  conditions,  in  view  of  the  fact  that 
probably  nearly  all  of  the  infested  orchards  and  districts  have  been 
located. 

INDIANA. 

The  first  case  of  infestation  was  brought  to  our  attention  in  May, 
1894,  and  subsequent  records  are  indicated  in  Bulletins  3 and  12.  As 
indicated  in  a map  sent  by  Prof.  J.  Troop,  horticulturist  of  the  State 
experiment  station,  the  scale  is  now  distributed  over  the  entire  State, 
occurring,  however,  in  less  than  half  of  the  counties.  It  occurs  in 
all  the  Ohio  River  counties,  and  Vanderburg  is  indicated  as  the  one 
worst  infested. 

IOWA. 

Iowa  hitherto  has  been  one  of  the  western  States  supposedly  free 
from  the  San  Jose  scale.  The  State  entomologist,  Mr.  II.  E.  Summers, 
reports  that  he  now  knows  of  but  one  infested  point  in  the  State,  con- 
fined to  a single  orchard  in  Louisa  County.  Some  other  cases  of 
introduction  of  the  scale  were  discovered  a few  years  ago,  but  were 
treated  in  such  a thoro  way  that  reinspection  during  the  last  three 
years  has  shown  no  further  development  of  scale.  No  San  Jose  scale 
has  been  found  in  any  nursery  in  the  State. 


24 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


KANSAS. 

Kansas  has  long  belonged  to  a group  of  middle  western  States  free 
from  the  San  Jose  scale.  I luring  the  present  year,  however,  this  scale 
insect  has  been  sent  to  us  for  determination  from  Dodge  City  on  apple 
twigs,  which  is  the  first  and  only  record  so  far  for  this  State,  on  the 
authorit}T  of  Prof.  E.  A.  Popenoe,  entomologist  of  the  State  experi- 
ment station.  A general  examination  of  the  orchards  of  the  State  has 
been  begun,  however,  and  additional  records  will  probably,  be  disn 
covered. 

KENTUCKY. 

But  one  record  of  the  San  Jose  scale  was  known  in  Kentucky  at  the 
time  of  the  publication  of  Bulletin  12.  Professor  Garman,  State  ento- 
mologist, now  reports  that  the  scale  is  still  not  generally  distributed 
in  the  State,  and  the  credit  for  this  he  believes  is  due  to  the  prompt 
institution  of  nursery  inspection  shortly  after  the  San  Jose  scale  came 
into  prominence  in  the  East.  Within  the  past  four  or  live  years,  how- 
ever, he  reports  an  increase  in  the  number  of  infested  localities,  par- 
ticularly in  northern  counties,  and  is  inclined  to  believe  that  in  some 
cases  the  stock  condemned  on  the  other  side  of  the  river  is  brought 
over  and  distributed  on  the  Kentucky  side.  The  infestation  is  con- 
fined to  the  river  counties  and  some  half  a dozen  interior  counties,  all 
lying  rather  above  the  median  line  of  the  State. 

LOUISIANA. 

The  early  records  of  infestation  in  Louisiana  are  given  in  detail  in 
Bulletin  3,  and  the  scale  is  supposed  to  date  in  this  State  from  about 
1891,  as  there  recorded.  The  present  situation  as  given  b}^  Mr. 
Wilmon  Newell,  the  entomologist  of  the  State  experiment  stations, 
indicates  12  distinct  localities  of  occurrence,  ranging  from  the  north- 
ern line  of  the  State  to  New  Orleans.  These  points  are  widely  sepa- 
rated, and  the  State  is  comparatively  free  from  the  scale.  Mr.  Newell 
states  that  no  very  thoro  inspection  of  all  the  orchard  sections  of 
the  State  has  been  made,  but  that  from  the  work  already  done  he 
believes  that  not  over  5 per  cent  of  the  orchards,  at  the  outside,  are 
infested.  But  one  small  nursery  is  known  to  be  infested,  and  the 
owner  of  this  nursery  is  not  permitted  to  place  his  stock  on  the  market. 

MAINE. 

The  San  Jose  scale  has  never  been  reported  from  Maine,  and  this  is  j 
confirmed  in  a recent  letter  from  Miss  Edith  M.  Patch,  the  entomolo- 
gist of  the  State  experiment  station. 


SUMMARY  OF  DISTRIBUTION"  AND  PRESENT  CONDITION.  25 


MARYLAND. 

Maryland  early  became  one  of  the  eastern  States  worst  infested  by 
he  San  Jose  scale,  and  one  that  suffered  most,  perhaps,  from  this 
>est.  It  also  received  the  most  energetic  earty  work  in  efforts  at 
sxtermination  and  control.  The  present  situation,  as  indicated  by 
vlr.  T.  B.  Symons,  State  entomologist,  shows  the  San  Jose  scale  to  be 
generally  distributed  over  the  entire  State,  with  the  exception  of  the 
wo  extreme  western  counties,  Garrett  and  Allegany,  the  former  hav- 
ng  the  San  Jose  scale  at  2 points  and  the  latter  at  15.  the  method 
)f  employing  State  inspectors  in  the  various  counties,  1,500,000  trees 
>f  various  kinds  have  been  inspected  each  year  for  the  past  four  y ears, 
md  from  the  records  thus  gained  18  per  cent  of  the  fruit  trees  in- 
spected are  infested,  and  65  per  cent  of  the  orchards,  and  this  estimate 
s believed  to  be  moderate. 


MASSACHUSETTS. 

The  presence  of  the  San  Jose  scale  was  determined  in  Massachusetts 
is  early  as  April  25,  1895,  as  recorded  in  Bulletin  3.  Additional  rec- 
>rds  are  given  in  Bulletin  12.  Prof.  H.  T.  Fernald,  summing  up  the 
present  situation,  says  that  he  was  forced  to  give  up  the  effort  of 
keeping  a complete  list  of  localities  known  to  be  infested  in  1900, 
inding  that  the  scale  was  practically  everywhere  in  Massachusetts 
iast  of  the  Connecticut  River.  At  the  present  time  it  may  be  found 
n almost  every  town  to  the  western  boundary  of  the  Connecticut 
Galley,  say  15  miles  west  of  the  river  on  the  average.  In  Berkshire 
Jountv,  which  lies  west  of  this,  he  has  no  records,  but  he  would  not 
ie  surprised  to  find  it  somewhere  in  that  region,  particularly  along 
he  Ilousatonic  Valley.  As  to  percentage  of  infestation,  he  says  that 
ibout  one-third  of  the  orchards  are  infested  to  a greater  or  less  degree, 
md  the  infested  orchards  are  particularly  the  more  recently  planted 
)nes.  In  the  older  orchards  infested  * replants  may  occasionally  be 
:ound.  Man}T  of  the  cases  of  infestation,  however,  are  of  ornamental 
:rees  and  shrubs  in  house  lots.  He  states  that  from  such  places  as 
he  Arnold  Arboretum  and  the  Metropolitan  Park  system  around 
Boston,  which  have  had  the  scale  for  nearly  fifteen  years,  it  has 
spread  in  all  directions,  and  that  in  Massachusetts  it  is  less  an  orchard 
problem  than  one  of  ornamental  plants. 

MICHIGAN. 

Michigan  was  not  known  to  be  infested  at  the  time  of  the  publica- 
tion of  Bulletin  3,  but  Professor  Barrows,  in  August,  1897,  reported 
II  localities  in  10  counties,  the  evidence  showing  that  the  scale  had 
been  present  in  the  State  since  1890.  The  present  situation  is  indi- 
cated on  a map  prepared  by  the  entomologist  of  the  State  experiment 


26 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


station,  Mr.  It.  H.  Pettit,  with  the  assistance  of  Professor  Taft,  and 

. * 

shows  scattering  infestation  thruout  the  southern  third  of  the  State, 
the  points  farthest  north  in  the  interior  away  from  the  influence  of 
Lake  Michigan  being  at  Ithaca  and  Otter  Lake,  which  are  both  rather 
beyond  the  anticipated  range  of  the  scale  insect.  It  is  not  shown, 
however,  that  the  extreme  points  in  the  range  are  points  of  permanent 
infestation. 

MINNESOTA. 

The  San  Jose  scale  has  not  been  reported  from  Minnesota. 

MISSISSIPPI. 

Mississippi  apparently  became  infested  with  the  San  Jose  scale  at 
the  same  time  (1891)  and  from  the  same  material  which  carried  this 
pest  to  Louisiana.  Mr.  Glenn  W.  Herrick,  professor  of  biology, 
Agricultural  College,  Miss.,  now  reports  the  scale  from  16  localities  in 
15  counties.  It  is  probable,  however,  that  in  portions  of  Mississippi 
and  Louisiana  the  San  Jose  scale  will  not  become  nearly  as  serious  a 
pest  as  in  northern  localities,  on  account  of  the  action  of  fungous 
diseases. 

MISSOURI. 

The  occurrence  of  the  San  Jose  scale  in  16  localities,  as  reported  byl 
Professor  Stedman,  is  noted  in  Bulletin  12.  Mr.  Stedman  now  states  I 
that  the  San  Jose  scale  has  practically  overrun  the  whole  of  St.  Louis  I 
County,  and  that  there  is  a bad  case  of  infestation  south  of  Independ-! 
ence,  another  just  west  of  Cape  Girardeau,  and  one  near  Charleston.  ! 

MONTANA. 

The  San  Jose  scale  has  never  been  reported  from  Montana.  Mr.' 
R.  A.  Cooley,  the  State  entomologist,  reports  that  during  his  seven- 
years  in  Montana  he  has  been  in  touch  with  all  parts  of  the  State,  and 
feels  sure  that  if  the  San  Jose  scale  occurred  there  he  would  have! 
known  of  it.  A few  reported  cases  investigated  have  turned  out  to 
be  of  other  species. 

NEBRASKA. 

The  San  Jose  scale  has  so  far  not  been  found  in  Nebraska,  as  reported 
by  Prof.  Lawrence  Bruner,  “ except  on  fruit  that  has  been  shipped) 
in,  principally  from  Colorado.”  In  view  of  its  nonoccurrence  in 3 
Colorado,  the  fruit  referred  to  must  have  come  from  California  or 
elsewhere. 

NEW  HAMPSHIRE. 

It  was  early  hoped  that  the  San  Jose  scale  would  not  be  able  to 
infest  much  of  the  fruit  regions  of  New  England,  but  this  hope  seems  j 
to  be  diminishing,  and  Prof.  Clarence  M.  Weed  reports  the  San  Jose  I 
scale  as  far  north  as  the  White  Mountain  region  in  New  Hampshire,  j 


SUMMARY  OF  DISTRIBUTION  AND  PRESENT  CONDITION.  27 


; o an  extent  that  it  is  seriously  destructive.  The  records  of  infes- 
e ation  show  the  occurrence  of  this  insect  in  New  Hampshire  in  the 
„f  astern  part  of  Manchester,  in  Dover  Point,  and  Intervale,  and  in 
(!I  turseries  at  Dover,  Epping,  and  Seabrook;  also  in  trees  from  these 
h iurseries  at  Rollinsford,  Lee,  and  Durham.  Mr.  E.  D.  Sanderson, 
Q{  he  present  entomologist  of  the  State  experiment  station,  adds  two 
idditional  localities,  one  in  Newington  and  the  other  at  North  Dan- 
ville. Mr.  Sanderson  reports  that  no  orchard  inspections  have  been 
nade,  and  that  as  practically  all  of  the  nursery  stock  comes  originally 
Tom  outside  of  the  State,  many  of  the  younger  orchards  are  probably 
nfested. 

NEW  JERSEY. 

it 

s New  Jersey,  responsible  for  much  of  the  original  distribution  of 
the  San  Jose  scale  in  the  East,  early  became  generally  infested,  as 
j recorded  in  Bulletins  3 and  12.  Dr.  J.  B.  Smith,  State  entomologist, 
j reports  that  this  scale  now  occurs  thruout  the  State  and  probably  in 
1 90  per  cent  of  the  orchards.  In  a general  way,  he  says,  those  dis- 
. tricts  that  are  longest  infested  are  in  a better  condition  than  those 
that  have  become  more  recently  infested,  because  growers  in  the  first 
instance  have  learned  how  to  deal  with  the  insect  to  the  best  advantage. 

NEVADA. 

The  occurrence  of  the  San  Jose  scale  in  Nevada  is  noted  in  Bulletin 
12  in  gardens  in  the  city  of  Reno.  We  have  records  also  from  Carson 
City  dating  from  1903  and  1901.  Prof.  J.  E.  Stubbs,  director  of  the 
State  experiment  station,  writes  that  the  insect  is  fairly  under  control 
in  the  State.  In  1904,  he  says,  and  prior  to  that  time,  its  ravages  in 
! three  or  four  counties  were  considerable,  and  farmers  complained  that 
they  were  losing  their  fruit  on  account  of  it.  At  the  session  of  the 
legislature  held  in  1903  a law  was  past  giving  authority  to  the  sev- 
eral counties  to  appoint  an  inspector  of  trees,  especially  fruit  trees. 
In  Washoe,  Ormsby,  Humboldt,  Elko,  and  Lincoln  counties  these 
inspectors  are  said  to  have  done  pretty  good  work  and  to  have 
checked  the  scale  by  spraying;  especially  was  this  true  in  the  counties 
of  Washoe  and  Ormsby. 

NEW  MEXICO. 

The  distribution  of  the  San  Jose  scale  in  New  Mexico  has  probably 
changed  very  little  since  the  publication  of  Bulletins  3 and  12,  and  no 
late  records  have  been  received  from  this  Territory. 

NEW  YORK. 

The  presence  of  the  scale  in  New  York  was  determined  in  August, 
1894,  and  the  early  records  are  noted  in  Bulletins  3 and  12.  The 
present  condition  of  this  scale  insect  in  New  York  has  been  reported  to 


28 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


us  by  Messrs.  M. V.  Slingerland  and  E.  P.  Felt.  Mr.  Slingerland  gives 
long  list  of  the  infested  localities  received  at  the  Cornell  experiment  sta 
tion,  and  reports  that  in  general  Long  Island,  the  Hudson  River  Valley 
and  Niagara  County  seem  to  be  the  worst-infested  sections.  Mr.  Felt’ 
records  were  made  after  consultation  with  Mr.  Atwood,  of  the  Stat 
department  of  agriculture,  who  has  direct  charge  of  nursery-inspec 
tion  work.  The  following  counties  are  reported  as  badly  infested 
either  because  of  the  pest  being  generally7  distributed  thruout  the  entir 
county  or  else  because  of  its  inflicting  considerable  damage  in  cer 
tain  restricted  areas:  Albany,  Cayuga,  Chemung,  Columbia,  Dutchess 
Erie,  Kings,  Nassau,  Niagara,  Ontario,  Orleans,  Putnam,  Queens 
Rensselaer,  Richmond,  Rockland,  Suffolk,  Wayne,  Westchester,  an< 
Yates.  It  is  also  known  to  occur  in  the  following  counties:  Broome 
Chautauqua,  Delaware,  Fulton,  Greene,  Jefferson,  Madison,  Monroe 
New  York,  Oneida,  Orange,  Schenectady-,  Schoharie,  Schuyler,  Sen 
eca,  Steuben,  Tompkins,  Ulster,  and  Washington.  Mr.  Felt  report! 
that  the  scale  may  be  safely  said  to  be  present  in  most  sections  when 
fruit  interests  are  at  all  extensive,  tho  not  always  generally"  distributed 

NORTH  CAROLINA. 

The  first  records  of  the  occurrence  of  the  San  Jose  scale  in  Nortl 
Carolina  are  given  in  Bulletin  12.  Mr.  R.  S.  Woglum,  acting 
entomologist  of  the  North  Carolina  department  of  agriculture,  has 
submitted  a map  indicating  general  infestation  thruout  the  State! 
represented  byr  over  fifty  counties,  in  which  the  number  of  point! 
infested  range  from  1 to  42.  These  points  are  definitely  known  eitheJ 
from  personal  observation  or  else  from  the  receipt  of  specimens  orl 
plants.  West  of  the  Blue  Ridge  Mountains  the  region  is  quite  free! 
from  the  scale,  only  four  infested  localities  being  known. 


No  San  Jose  scale. 


NORTH  DAKOTA. 
OHIO. 


The  early  conditions  in  Ohio,  as  determined  by  Prof.  F.  M.  Webster, 
are  reported  in  Bulletins  3 and  12;  Mr.  A.  F.  Burgess,  chief  State! 
inspector,  gives  the  following  summary  of  the  present  conditions: 


Counties  having  no  infested  orchards 26 

Counties  with  1 infested  orchard  locality 27 

Counties  with  2 infested  orchard  localities 10 

Counties  with  3 infested  orchard  localities 10 

Counties  with  more  than  3 infested  orchard  localities  or  hav- 
ing large  infested  areas  or  numerous  small  outbreaks 15 


The  majority  of  the  larger  cities  of  the  State  are  more  or  less 
infested. 

These  points  of  infestation  cover  the  State  pretty7  generally. 


SUMMARY  OF  DISTRIBUTION  AND  PRESENT  CONDITION. 


29 


OKLAHOMA. 

| The  first  records  of  the  San  Jose  scale  In  Oklahoma  were  received 
L 1904,  on  Japan  plum  from  Mulhall.  We  have  since  received  it,  in 
[905,  on  peach  from  Stillwater  and  El  Reno.  Mr.  J.  F.  Nicholson, 
entomologist  of  the  agricultural  experiment  station,  reports  that  the 
Lale  has  been  found  to  a limited  extent  in  five  places  in  the  Territory, 
Lmely,  Mulhall,  Shawnee,  El  Reno,  Wellston,  and  Chandler.  All  of 
diese  cases  are  trees  in  city  gardens. 

OREGON. 

Mr.  A.  B.  Cordley,  referring  to  present  conditions  in  Oregon,  states 
that  to  enumerate  the  localities  where  the  San  Jose  scale  is  found  would 
be  practically  to  include  all  places  where  fruit  is  grown.  He  says  that 
it  occurs  in  a very  large  proportion  of  the  orchards  in  western  Oregon, 
from  Ashland  to  Portland,  particularly  those  along  the  lines  of  rail- 
roads or  in  the  vicinity  of  towns,  there  being  scattered  orchards  back 
toward  the  foothills  which  the  San  Jose  scale  has  not  yet  reached.  It 
occurs  also  between  Portland  and  Astoria,  along  the  Columbia  River; 
is  present  in  the  Hood  River  Valley;  in  the  Walla  Walla  Valley  in  the 
vicinity  of  Milton  and  Freewater,  and  in  the  Grande  Ronde  Valley  m 
the  vicinity  of  Vale  and  Ontario.  There  are,  however,  large  areas  of 
central  and  southern  Oregon,  remote  from  the  railroads,  where  little 
fruit  is  grown,  that  the  scale  has  not  yet  reached.  It  is  noted,  how- 
ever, that  the  scale  does  no  great  injury  except  in  small  farm  orchards 
or  those  that  are  neglected,  and  that  in  all  the  large  orchards  the  lime, 
sulfur,  and  salt  mixture  as  a winter  spray  is  in  general  use. 

PENNSYLVANIA. 

The  San  Jose  scale  became  early  established  in  Pennsylvania  from 
New  Jersey  nurseries,  bui;  the  subject  of  San  Jose  scale  control  was  not 
taken  up  as  early  in  this  State  as  in  neighboring  States,  so  that  the 
conditions  at  the  outset  were  not  well  known.  Both  Prof.  H.  A.  Sur- 
face, economic  zoologist  of  the  State,  and  Mr.  George  C.  Butz,  the 
horticulturist  of  the  agricultural  experiment  station,  agree  in  the  state- 
ment that  the  San  Jose  scale  is  now  so  widespread  in  Pennsylvania 
that  there  is  scarcely  a county  that  has  not  points  of  infestation.  It 
occurs  in  practically  all  the  important  fruit  regions  of  the  State,  and 
in  many  private  and  public  grounds,  especially  in  the  portion  of  Penn- 
sylvania lying  east  of  the  Allegheny  Mountains.  Mr.  Butz  reports 
that  probably  20  per  cent  of  the  orchards  are  more  or  less  infested. 
Professor  Surface  has,  with  the  assistance  of  30  inspectors,  taken  up 
active  warfare  against  the  scale,  inspecting  orchards  and  nurseries  and 
trees  in  parks  and  giving  demonstrations  in  methods  of  suppressing 
it.  He  states  that  he  has  not  found  the  scale  in  the  three  northeastern 


30 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


counties  of  the  State,  nor  in  some  of  the  counties  northwest  of  th 
center  of  the  State,  such  as  Cameron,  Elk,  Forest,  McKean,  an 
Warren. 

RHODE  ISLAND. 

No  records  from  Rhode  Island  had  been  received  up  to  the  time  o 
the  publication  of  Bulletin  12,  in  1898,  but  Mr.  A.  E.  Stene,  of  th 
College  of  Agriculture  and  Mechanic  Arts,  states  that  the  scale  ha 
now  spread  over  almost  the  entire  State,  and  nearly  every  orchan 
where  planting  has  been  done  in  the  last  ten  years  is  more  or  les, 
infested.  There  are  a few  old  orchards  where  no  new  trees  hav< 
recently  been  set  that  are  still  free  from  the  scale,  it  is  believed  tha 
four-fifths  of  the  orchards  in  the  State  are  infested. 


SOUTH  CAROLINA. 

But  a single  record  for  South  Carolina  had  been  received  up  t( 
the  time  of  the  publication  of  Bulletin  12,  largely,  as  there  indicated 
for  the  reason  that  there  had  been  no  State  entomologist,  and  nc 
work  of  inspection  had  been  done.  The  records  which  have  come 
to  this  office  from  South  Carolina  now  number  10,  and  represent  \ 
different  localities  distributed  miscellaneously  over  the  State.  Natu 
iaHy,  very  few  of  the  actual  records  would  come  to  us,  and  the  indi- 
cations are  that  the  State  is  pretty  generally  infested.  Mr.  C.  E. 
Chambliss,  the  entomologist  of  the  experiment  station,  now  reports 
24  infested  localities,  all  of  which  had  the  scale  prior  to  1900. 


SOUTH  DAKOTA. 


No  San  Jose  scale  has  yet  been  reported  from  South  Dakota.  Mr. 
W . A.  Wheeler,  the  entomologist  of  the  experiment  station,  states  that 
he  has  inspected  nurseries  of  South  Dakota  for  two  years,  and  has  not 
found  the  San  Jose  scale  in  any  nursery.  It  has  been  introduced  with 
stock  received  by  the  college  from  other  States,  but  has  always  been 
speedily  disposed  of  when  received,  and  so  far  is  not  known  to  infest 
any  of  the  orchards. 


TENNESSEE. 

A single  locality  was  recorded  for  the  San  Jose  scale  in  the  eastern 
portion  of  the  State  in  Bulletin  12.  Since  that  time  the  number  of 
records  for  the  San  Jose  scale  which  have  come  to  this  office  for  deter- ! 
mination  has  increased  to  14.  These  are  distributed  generally  over  the  L 
State,  and  indicate  rather  widespread  infestation,  and  naturally  very! 
much  more  than  is  shown  by  the  material  which  has  been  sent  to  the; 
Department. 

A lecent  letter  from  Mr.  G.  M.  Bentley,  assistant  entomologist, 
gives  the  information  that  no  complete  survey  of  the  State  has  been ; I 


SUMMARY  OF  DISTRIBUTION  AND  PRESENT  CONDITION.  31 


lade,  but,  roughly  speaking,  30  per  cent  of  the  nurseries  are  more  or 
ess  infested,  and  in  eastern  Tennessee  the  San  Jose  scale  is  very  gen- 
rally  present;  but  the  section  of  the  State,  notably  Franklin  County, 
/here  most  of  the  nurseries  are  located,  is  free  from  the  pest.  The 
xtreme  western  part  of  the  State,  in  the  Memphis  section,  is  also 
>rett}7  badly  infested.  No  general  orchard  inspection  of  the  State  has 
»een  made. 

TEXAS. 

Eight  localities  were  reported  for  Texas  in  Bulletin  12.  The  scale 
3 now  fairly  widely  distributed  in  the  State,  the  records  of  this  office 
lumbering  19,  some  of  these,  however,  representing  the  same  district. 
The  localities  cover,  generally  speaking,  the  eastern  half  of  the  State, 
tamely,  the  nonarid  portion  where  fruit  growing  is  followed  to  a 
greater  or  less  extent.  Prof.  A.  F.  Conradi,  the  State  entomologist, 
tas  records  of  the  insect’s  occurrence  in  Bexar,  Brazonia,  Calhoun, 
Jherokee,  Comal,  Comanche,  Eastland,  Erath,  Galveston,  Harris, 
Harrison,  Hopkins,  Hunt,  Valverde,  Wharton,  and  Wood  counties. 

UTAH. 

No  San  Jose  scale  was  recorded  for  Utah  in  either  Bulletin  3 or  12. 
n 1899  it  was  sent  to  us  for  determination  from  both  Ogden  and 
^ogan.  Mr.  E.  D.  Ball,  the  entomologist  of  the  State  experiment 
station,  reports  that  he  is  unable  to  give  the  exact  localities  of  the 
)ccurrence  of  this  insect,  but  states  that  it  is  pretty  widely  spread  in 
;he  central  section  of  the  State,  doing,  however,  little  damage.  It 
seems  to  be  controlled  by  the  twice-stabbed  ladybird.  The  commer- 
nal  orchards,  as  a rule,  are  practically  free.  A good  deal  of  spraying 
aas  been  done  with  the  standard  lime-sulfur  wash. 

VERMONT. 

The  occurrence  of  the  San  Jose  scale  in  Vermont  was  brought  to 
3ur  notice  in  1899.  Mr.  William  Stuart,  horticulturist  of  the  State 
experiment  station,  says  that  it  is  now  known  to  occur  in  only  two 
localities,  namely,  Charlotte,  Chittenden  County,  and  Orwell,  Rutland 
bounty ; in  both  instances  occurring  in  only  one  orchard. 

VIRGINIA. 

The  details  of  the  early  records  in  Virginia  are  given  in  Bulletin  3 and 
in  Bulletin  12.  A great  many  new  records  have  been  received  from 
Virginia  and  more  material  has  come  to 'this  Bureau  for  determination 
from  Virginia  than  from  any  other  State  except  Pennsylvania.  Mr. 
J.  L.  Phillips,  State  entomologist,  in  reply  to  our  circular  letter  refers 
8449— No.  62—06 3 


32 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


to  his  publications,  in  which  it  appears  that  the  San  Jose  scale  is 
recorded  from  78  counties.  Many  orchards  in  all  of  the  counties  are 
still  free  from  the  scale,  but  infestation  is  very  general  thruout  the 
State. 

WASHINGTON. 

The  State  of  Washington  was  early  infested  with  the  San  Jose  scale 
from  California,  and  at  the  time  of  the  publication  of  Bulletin  3,  in 
1896,  the  f ruit-growing  regions  were  pretty  well  dotted  with  this  pest. 
Mr.  A.  L.  Melander,  assistant  entomologist,  submits  a map  which  is 
about  to  be  published  in  a bulletin  showing  the  distribution  of  this 
insect.  It  indicates  the  occurrence  of  the  scale  in  the  western  settled 
section  of  the  State,  where  fruit  growing  is  important,  following  the 
river  valleys,  but  with  some  important  scattering  districts  on  the  west 
side  of  the  mountains,  where  it  seems  to  have  a precarious  foothold. 
It  is  little  dreaded  by  orchardists,  and  fruit  trees  are  commonly  sprayed 
with  the  lime,  sulfur,  and  salt  wash  in  February,  and  one  treatment 
is  reported  to  be  effective  for  several  years. 

WISCONSIN. 

Wisconsin  is,  on  the  authority  of  Mr.  E.  P.  Sandsten,  horticulturist 
of  the  State  experiment  station,  now  free  from  the  San  Jose  scale. 
The  only  occurrence  of  this  pest  in  the  State  was  three  years  ago,  in 
the  extreme  southern  part,  and  it  was  here  stamped  out  by  the  prompt 
adoption  of  radical  measures. 

WYOMING. 

Mr.  B.  C.  Buffum,  director  of  the  agricultural  experiment  station, 
reports  that  the  San  Jose  scale  has  not  yet  appeared  in  Wyoming. 
There  are  but  few  orchards  in  bearing,  and  these  are  believed  to  be 
free  from  this  pest. 

WEST  VIRGINIA. 

The  San  Jose  scale  was  first  noticed  in  West  Virginia  in  1896. 
Many  examples  of  the  San  Jose  scale  in  this  State  have  been  sent  to 
this  office  for  determination,  showing  the  scale  to  be  very  generally 
distributed. 

The  recent  reports  of  the  West  Virginia  experiment  station,  notably 
those  for  1903-4  and  1904-5,  and  later  records  received  from  the 
entomologist  of  the  experiment  station,  Mr.  W.  E.  Rumsey,  indicate 
very  general  infestation  thruout  the  State,  conditions  being  similar 
to  those  in  Virginia.  Nevertheless,  while  there  are  hundreds  of 
infested  orchards  and  several  infested  nurseries,  the  great  mass  of  the 
orchards  and  nurseries  are  still  free  from  scale.  A very  careful 
nursery  and  orchard  inspection  is  maintained  in  West  Virginia,  and 


THE  RELATION  OF  CLIMATE  TO  SPREAD. 


33 


;he  actual  conditions  of  infestation  are  perhaps  as  well  known  in  this 
•>tate  as  in  any  other.  In  many  localities  the  scale  is  held  in  check  by 
his  careful  system  of  inspection  and  by  the  prompt  and  thoro 
idoption  of  the  remedial  treatment. 


CANADA. 

On  the  authority  of  Dr.  James  Fletcher,  the  Dominion  entomolo- 
gist, the  San  Jose  scale  infestation  in  the  eastern  portion  of  Canada  is 
confined  to  the  Niagara  Peninsula  and  counties  along  the  north  shore 
>f  the  west  end  of  Lake  Erie.  It  has  also  been  found  in  several  locali- 
ies  in  British  Columbia,  having  reached  this  province  in  its  northward 
nigration  along  the  Pacific  slope. 

THE  RELATION  OF  CLIMATE  TO  SPREAD. 

This  subject  was  rather  carefully  considered  in  both  Bulletins  3 and 
.2,  in  connection  with  the  climatic  districts  or  life  zones  established 
>y  Dr.  C.  Hart  Merriam,  within  which  particular  animals  thrive 
tnd  outside  of  which  they  fail  to  establish  themselves.  These 
ife  zones  as  thus  limited  have  a special  value  in  indicating  the 
>robable  spread  of  many  injurious  insects,  and  seem  to  be  par- 
icularly  significant  in  the  case  of  the  San  Jose  scale.  These  life  zones 
a*e:  The  tropical,  occupying  small  areas  in  Florida  and  southern  Texas; 
he  lower  and  upper  austral,  covering  the  bulk  of  the  United  States; 
,nd  the  transition  zone,  coming  between  the  last  and  the  boreal  zone 
>f  Canada  northward.  These  zones  will  be  better  understood  by  refer- 
;nce  toihe  accompanying  map  (PI.  V).  The  early  records  led  to  the 
relief  that  the  San  Jose  scale  would  be  practically  limited  to  the  upper 
jid  lower  austral  zones,  and  that  the  important  fruit  districts  in  the 
lorthern  United  States  and  in  elevated  mountain  regions,  represented 
>y  the  transition  zone,  would  be  slightly  if  any  infested.  In  the  main, 
he  records  of  the  distribution  of  the  San  Jose  scale  have  confirmed 
! his  belief.  Nevertheless,  the  scale  has,  in  a number  of  instances, 
appeared  well  into  the  transition  zone  as  fixt  by  Doctor  Merriam, 
hotably  in  Massachusetts,  in  New  York,  in  Michigan,  and  a few  other 
boints;  but  in  most  of  these  cases  the  evidence  gained  from  the  rela- 
ion  of  other  animals  and  plants  would  indicate  that  the  transition  and 
ipper  austral  zones  were  not  correctly  charted,  so  that  in  general  the 
>elief  in  the  immunity  of  the  transition  zone  holds. 

As  pointed  out  b}^  Doctor  Howard  in  Bulletin  12,  the  coastal  law 
vhich  brings  about  the  intermingling  of  northern  and  southern  forms 
nil  probably  justify  the  eastern  Massachusetts  occurrences.  Other 
occurrences  in  Massachusetts  are  justified  by  the  river-valley  law  in 
elation  to  the  Connecticut  River,  and  Doctor  Merriam  admits  that  his 
ine  across  the  southern  peninsula  of  Michigan  is  not  very  accurately 


34 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


drawn.  Special  topographical  conditions  and  protecting  mountains 
will  probably  account  for  other  divergences. 

In  the  lower  austral  and  tropical  regions  the  San  Jose  scale,  as 
pointed  out  by  Doctor  Howard,  may  not  prove  as  injurious  as  in  the 
upper  austral,  and  this  follows  the  general  rule  regarding  armored 
scale  insects  in  warm  countries.  Armored  scales  rarely  appear  or 
thrive  in  the  moist  Tropics,  as  shown  b\r  the  explorations  of  the  writer 
in  the  East  and  West  Indies.  Fungous  diseases,  which  thrive  in  warm 
and  moist  climates,  are  the  principal  agency  in  keeping  such  scale 
insects  in  check,  and  in  the  case  of  the  San  Jose  scale  the  common 
scale  fungus  Sphderostilbe  coccophila  has  already  done  good  work  in 
Florida  and  other  portions  of  the  lower  austral  zone.  Moisture  is  a 
prerequisite  in  the  case  of  this  disease,  and  little  benefit  comes  from 
it  in  the  drier  portions  of  this  zone.  Too  much  stress,  however,  should 
not  be  put  on  zonal  limitations,  and  there  may  always  be  outbreaks 
of  longer  or  shorter  standing  in  the  borders  of  the  transition  region. 

HABITS  AND  LIFE  HISTORY. 

NATURE  OF  THE  DAMAGE. 

The  San  Jose  scale,  as  alread}7  stated,  occurs  on  all  parts  of  the 
plant — limbs  (PI.  I;  PI.  YI,  fig.  1),  leaves,  and  fruit  (PI.  Yl,  fig.  2). 
As  the  plant  becomes  badly  infested  the  scales  lie  very  close  together 
on  the  limbs,  frequently  overlapping,  sometimes  with  several  young 
ones  clustering  over  the  surface  of  an  old  mature  scale.  The  gen- 
eral appearance  which  they  present  is  of  a grayish,  very  slightly 
roughened,  scurfy  deposit.  The  natural  rich  reddish  color  of  the 
young  limbs  of  peach,  pear,  and  apple  is  quite  obscured  when  these 
trees  are  thickly  infested,  and  they  have  then  every  appearance  of 
being  coated  with  ashes.  When  the  scales  are  crusht  by  scraping, 
a yellowish,  oily  liquid  will  appear,  resulting  from  the  mashing  of 
the  soft,  yellow  insects  beneath  the  scales.  Examined  under  a hand 
lens  during  the  summer,  numbers  of  the  little  orange-colored  larva? 
will  be  seen  running  about,  and  the  snowy  white  young  scales  will  bei 
interspersed  with  the  old  brown  or  blackened  mature  scales.  The 
appearance  presented  at  this  time  under  the  lens  is  shown  in  fig.  2. 1 
Yery  frequently  the  scale  has  a marked  tendenc}Ho  infest  the  extrem- 
ities of  the  branches  and  twigs.  This  is  particularly  noticeable  with 
pear.  As  usually  found  on  peach,  the  scale  is  massed  often  more 
densely  on  the  older  growth,  and  works  out  more  slowly  toward  the] 
new  wood. 

The  leaves  are  much  less  apt  to  bear  scales,  but  in  severe  cases  the 
upper  surface  particularly  becomes  infested,  the  scales  frequently  rang- 
ing in  two  or  more  quite  regular  rows  on  either  side  of  the  midrib. 


Plate  v. 


[>  STATES 


Plate  v. 


Bul.62,  Bureau  of  Entomology,  U.  S.  Dept,  of  agriculture. 


Corrected  to  DeccitiWasev 


LIFE  ZONES  OF  THE  UNITED  STATES 

BY 

C.  HART  MERRIAM 


Bui.  62,  Bureau  of  Cntorr.ology,  U.  S.  Dept,  of  Agriculture 


Plate  VI. 


Fig.  1 .—Large  Apple  Trees  with  Lower  Limbs  Killed  by  the  San  Jose  Scale, 
Youngstown,  N.  Y.  'Original.' 


Fig.  2,— Apple  Infested  with  San  Jose  Scale.  Slightly  Enlarged  (Original). 


NATURE  OF  THE  DAMAGE. 


35 


The  male  scales  are  more  numerous  on  the  leaves  than  the  females. 
The  infested  leaves  turn  purplish  brown. 

The  San  Jose  scale  was  formerly  supposed  to  differ  from  all  others 
in  the  peculiar  reddening  effect  which  it  produces  upon  the  skin  of  the 
fruit  and  of  tender  twigs.  This,  however,  sometimes  occurs  with  other 
scales,  but  is  a particularly  characteristic  feature  of  this  insect,  and 
renders  it  easy  to  distinguish.  The  encircling  band  of  reddish  dis- 
coloration around  the  margin  of  each  female  scale  is  very  noticeable 


Fig.  2. — Appearance  of  San  Jose  scale  ( Aspidiotus  perniciosus)  on 
bark:  a,  infested  twig,  natural  size;  b,  bark  as  it  appears  under 
hand  lens,  showing  scales  in  various  stages  of  development  and 
young  larvae.  (From  Howard  and  Marlatt.) 

on  fruit,  especially  pears.  This  appearance,  however,  sometimes  so 
closely  resembles  the  small  spots  on  fruit  produced  by  a common  fungus, 
Entomosjporiwn  maculatiwn  Lev.,  as  to  require  close  examination  with 
a lens  to  distinguish  it.  Fruit  severely  attacked  becomes  distorted, 
rough,  and  pitted,  frequently  cracking,  and  may  eventually  fall  prema- 
turely or  at  least  become  unmarketable. 

The  cambium  layer  of  }Toung  twigs  where  the  scales  are  massed 
together  is  usually  stained  deep  red  or  purplish,  and  when  the  scale  is 
only  scatteringly  present  the  distinctive  purplish  ring  surrounding  each 


THE  SAN  JOSE  OR  CHINESE  SCAI. 


36 

is  almost  as  noticeable  on  young  twigs  as  on  fruit,  and  is  of  the  greatest 
service  in  facilitating  the  inspection  of  trees  which  have  been  subject 
to  possible  Contagion.  The  almost  microscopic  }7oung  scale  might  easily 
elude  the  most  careful  search,  but  the  striking  circling  ring  makes  it 
a comparatively  conspicuous  object  without  the  aid  of  a glass. 

If  the  tree  survives  the  attack  the  infested  wood  eventually  becomes 
knotty  and  irregular,  partly  from  the  sapping  of  the  juices  by  the  insect, 
and  also  without  doubt  largely  from  the  poisoning  of  the  sap  of  the 
cambium  layer  by  the  punctures  of  the  insect,  as  indicated  by  the  dis^ 
coloration.  Young  peach  trees  will  ordinarily  survive  the  scale  only 
two  or  three  years.  Pears  are  sometimes  killed  outright,  but  generally 
maintain  a feeble,  sickly  existence,  making  little  or  no  growth  for  a 
somewhat  longer  period. 

FOOD  PLANTS. 

The  San  Jose  scale  may  attack  almost  any  deciduous  plant,  including! 
fruits,  ornamentals,  and  the  various  shade  trees.  Food-plant  lists 
were  published  in  Bulletins  3 and  12  of  this  Bureau,  and  several  sub- 
sequent writers  have  given  lists,  with  important  additions.  The  mostl 
careful  investigation  of  the  subject,  relating  particularly  to  ornamentall 
trees  and  shrubs,  but  also  to  fruit  trees,  as  these  are  often  planted  forp 
ornament,  was  that  conducted  by  the  State  entomologist  of  Connecti-J 
cut,  ^lr.  W.  E.  Britton,  who  sent  out  a circular  letter  to  the  entomol- 
ogists and  horticultural  inspectors  of  the  various  States  asking  fori 
data  under  three  headings,  namely:  (1)  Plants  commonly  infested;! 
(2)  those  occasionally  or  rarely  infested;  (3)  those  not  infested. I 
Forty-five  replies  were  received,  and  from  these  and  other  records  his| 
list  was  prepared.  This  list  I have  reproduced,  together  with  hisB 
following  explanatory  paragraphs." 

List  of  Hardy  Trees,  Shrubs,  and  Vines. 

COMMONLY  OR  BADLY  INFESTED. 

Acacia  sp.  Lintner,  Felt,  N.  Y. ; Alwood,  Va. 

AJcebia  sp.  Felt,  N.  Y. 

Akebia  quinata  Deeaisne.  Alwood,  Va. 

Amelanchier  canadensis  Medic.,  and  other  species.  Shad-bush,  Juneberry.  Britton,  1 
Koehler,  Conn. ; Alwood,  Va. 

Citrus  tr if oliuta  Linn.  Scott,  Ga. ; Alwood,  Va. ; Gossard,  Fla. 

Cornus  alba  Linn.  var.  sibirica  Lodd.  Britton,  Conn. 

Cornus  baileyi  Coult  & Evans.  Gould  (in  N.  Y.). 

Cornus  sanguinea  Linn.  Britton,  Conn. 

Cotoneaster  sp.?  Britton,  Conn.;  Lintner,  Felt,  N.  Y.;  Card,  R.  I. 

Cotoneaster  v ulgaris  Lind  1.  Alwood,  Va. 

« Report  of  the  Connecticut  Agricultural  Experiment  Station,  1902,  Part  II,  2d 
Report  of  the  Entomologist,  pp.  132-138. 


PLANTS  COMMONLY  OR  BADLY  INFESTED. 


37 

,!  Crataegus  sp.  Hawthorn.  Britton,  Conn.;  Lintner,  Felt,  N.Y.;  Alwood,Va. ; Smith, 
N.  J. 

| Crataegus  cordatci  Soland.  Koehler,  Conn. 

Crataegus  oxyacantha  Linn.  English  hawthorn.  Britton,  Koehler,  Conn. 

Crataegus  coccinea  Linn.  Koehler,  Conn. 

Crataegus  crus-gatti  Linn.  Koehler,  Conn. 

Cydonia  vulgaris  Pers.  Common  quince.  Britton,  Conn.;  Lintner,  N.  Y. ; Alwood, 
Ya. 

Cydonia  japonica  Pers.  Japanese  or  flowering  quince.  Britton,  Koehler,  Conn.; 

Lintner,  N.  Y.;  Alwood,  Va. ; Johnson,  Md. 

Fagus  sylvaiica  Linn.  var.  purpurea  Ait.  European  purple-leaved  beech.  Smith, 

N.  J. 

1 Juglans  sieboldianu  Maxim.  Japanese  walnut.  Britton,  Conn. ; Alwood,  Ya.;  Sher- 
man, N.  C. ; Smith,  N.  J. 

Ligustrum  vulgar e Linn.  Common  privet.  Alwood,  Va. 

; Populus  sp.  Poplar.  Britton,  Conn. ; Smith,  N.  J. ; Sanderson,  Del. ; Felt,  N.  Y. 
Populus  ddtoides  Marsh.  Carolina  poplar.  Britton,  Conn.;  Rolfs  & Quaintance, 
Fla.;  Alwood,  Va. 

Populus  nigra  Linn.  var.  italica  Du  Roi.  Lombardy  poplar.  Britton,  Koehler,  Conn.; 
Rolfs  & Quaintance,  Fla.;  Alwood,  Va. 
j Prunus  amygdalus  Stokes.  Almond.  Lintner,  N.  Y. ; Alwood,  Va. 

| Prunus  armeniaca  Linn.  Apricot.  Lintner,  Felt,  N.  Y.;  Alwood,  Va.;  Smith,  N.  J. 

! Prunus  avium  Linn.  Sweet  cherry.  Britton,  Conn.;  Lintner,  Felt,  N.  Y. ; Alwood, 
Va.;  Smith,  N.  J.;  Cockerell,  N.  Mex. 

Prunus  pumila  Linn.  Koehler,  Conn. 

Prunus  puinila  var.  besseyi Waugh.  Sand  cherry.  Alwood,  Va. 

Prunus  cerasifera  Ehrh.,  var.  atropurpurea  Dipp.  (P.  pissardi).  Purple-leaved  plum. 
Britton,  Conn.;  Felt,  N.  Y. 

Prunus  domestica  Linn.  European  plum.  Britton,  Conn.;  Alwood,  Va. 

Prunus  hortulana  Bailey . Wild  goose  plum.  Alwood,  Va. 

Prunus  japonica  Thunb.  Flowering  almond.  Britton,  Conn.;  Felt,  N.  Y. 

Prunus  niaritima  Waugh.  Beach  plum.  Koehler,  Britton,  Conn. 

Prunus  per  sica  Sieb.  & Zucc.  Peach.  Britton,  Koehler,  Conn.;  Lintner,  Felt, 
N.  Y. ; Alwood,  Va. ; Cockerell,  N.  Mex. 

Prunus  triflora  Roxbg.  Japanese  plum.  Britton,  Koehler,  Conn.;  Alwood,  Va. 
Prunus  serotina  Ehrh.  Koehler,  Conn. 

Prunus  virginiana  Linn.  Chokecherry.  Koehler,  Conn. 

Ptelea  trifoliata  Linn.  Hop  tree.  Fernald,  Mass. 

Pyrus  communis  Linn.  Pear.  Britton,  Koehler,  Conn.;  Lintner,  Felt,  N.  Y. ; 

Alwood,  Va. ; Cockerell,  N.  Mex. 

Pyrus  sinensis  Lindl.  Sand  pear,  including  Kieffer.  Alwood,  Va. 

Pyrus  baccata  Linn.  Koehler,  Conn. 

Pyrus  malus  Linn.  Apple.  Britton,  Koehler,  Conn.;  Lintner,  Felt,  N.  Y.;  Alwood, 
Va. ; Doten,  Nev. ; Cockerell,  N.  Mex. 

Pyrus  sp.  Crab  apple.  Britton,  Conn. 

Ribes  oxyacanthoides  Linn.  Gooseberry.  Britton,  Conn.:  Lintner,  Felt,  N.  Y. ; 
Alwood,  Va. ; Troop,  Ind. 

Ribes  aureum  Pursh.  Missouri  or  flowering  currant.  Lintner,  N.  Y. 

Ribes  rubrum  Linn.  Currant.  Britton,  Conn.;  Lintner,  Felt,  N.  Y. 

Ribes  nigrum  Linn.  Black  currant.  Alwood,  Va. 

Rosa  sp.  Britton,  Conn.;  Lintner,  N.  Y.;  Alwood,  Va. ; Cockerell,  N.  Mex.;  Bur- 
gess, Ohio;  Troop,  Ind.;  Gould,  Md. ; Scott,  Ga. 

Rosa  Carolina  Linn.  Koehler;  Conn. 

Rosa  lucida  Ehrh.  Koehler,  Conn. 


38 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


Rosa  virginiana,  Mill.  Koehler,  Conn. 

Rosa  rugosa  Thunb.  Britton,  Koehler,  Conn. 

Salix  sp.  Willow.  Britton,  Conn.;  Felt,  N.  Y. ; Sanderson,  Del. 

Salix  lucida  Muhl.  Koehler,  Conn. 

Salix  pentandra  Linn.  Laurel-leaved  willow.  Lintner,  N.  Y.;  Alwood,  Ya. 

Salix  vitellina  Linn.  Koehler,  Conn. 

Salix  baby l onica  Linn.  Weeping  willow.  Lintner,  N.  Y. ; Alwood,  Va 
Salix  humilis  Marsh.  Koehler,  Conn. 

Salix  incana  Schrank.  Koehler,  Conn. 

Sorbus  sp.  Mountain  ash.  Felt,  N.  Y. ; Hunter,  Kans. 

Sorbus  americana  Marsh.  American  mountain  ash.  Britton,  Koehler,  Conn.; 
Alwood,  Ya. 

Sorbus  aucuparia  Linn.  European  mountain  ash.  Britton,  Koehler,  Conn. 

Sorbus  melanocarpa  C.  Koch.  ( Aronia  nigra  Koehne).  Black  chokeberry.  Koehler, 
Conn. 

Symphoricarpos  racemosus  Michx.  Snowberry.  Felt,  N.  Y. ; Smith,  N.  J. 

Syringa  vulgaris  Linn.  Common  lilac.  Burgess,  Ohio;  commissioner  of  agriculture, 
N.  Y. ; Troop,  Ind. ; Alwood,  Va. 

Syringa  persica  Linn.  Persian  lilac.  Britton,  Conn. 

Tilia  sp.  Basswood,  linden.  Britton,  Conn.;  Lintner,  commissioner  of  agriculture, 
N.  Y. 

Tilia  americana  Linn.  American  linden  or  basswood.  Britton,  Conn. ; Alwood,  Va. 
Toxylon  pomiferum  Raf.  Osage  orange.  Britton,  Conn.;  Lintner,  Felt,  N.  Y.; 
Alwood,  Ya. 

Ulmus  sp.  Elm.  Lintner,  N.  Y. ; Webster,  Ohio;  Troop,  Ind. 

Ulmus  americana  Linn.  American  elm.  Britton,  Koehler,  Conn.;  Alwood,  Va. 
Ulmus  campestris  Smith.  English  or  European  elm.  Britton,  Conn.;  Felt,  N.  Y. ; 
Smith,  N.  J. 

OCCASIONALLY  OR  RARELY  INFESTED. 

Acer  sp.  Maple.  Webster,  Burgess,  Ohio;  Fernald,  Mass. ; Butz,  Pa. ; commissioner 
of  agriculture,  N.  Y. 

Acer  saccharinum  Linn.  Silver  maple.  Gould,  Md. ; Alwood,  Ya. ; Hunter,  Kans. ; 
Felt,  N.  Y. 

Acer  saccharinum.  Weir’s  cut-leaved.  Felt,  N.  Y. 

Acer  platanoides  Linn.  Norway  maple.  Gould,  Md. 

Actinidia  arguta  Miq.  (A.  polygama).  Alwood,  Va. 

JEsculus  hippocaslanum  Linn.  Horse-chestnut.  Felt,  commissioner  of  agriculture, 
N.  Y. ; Burgess,  Parrot,  Green,  Ohio.  ' 

Alnus  sp.  Alder.  Felt,  N.  Y. ; Alwood,  Va. 

Ampelopsis  quinquefolia  Michx.  Virginia  creeper.  Alwood,  Va. 

Betula  sp.  Birch.  Felt,  N.  Y. 

Betula  alba  Linn.  Cut-leaved  white  birch.  Britton,  Conn.;  Rolfs  & Quaintance,  Fla. 
Buxus  sp.  Box.  Britton,  Conn. 

Castanea  americana  Raf.  Chestnut.  Rolfs  & Quaintance,  Fla.;  Alwood,  Va. ; 
Felt,  N.  Y. 

Catalpa  sp.  Rolfs  & Quaintance,  Fla. 

Catalpa  bignonioides  Walt.  Common  catalpa.  Alwood,  Va. 

Ceanothus  americanus  Linn.  Koehler,  Conn. 

Celtis  occidentalis  Linn.  Koehler,  Conn. 

Cercidiphyllum  japonicum  Sieb.  & Zucc.  Britton,  Conn. 

Citrus  aurantium  Linn.  Gossard,  Fla. 

Cornus  allernifolia  Linn.  Koehler,  Conn. 

Cornus  stolonifera  Michx.  Koehler,  Conn. 


PLANTS  OCCASIONALLY  OR  RARELY  INFESTED. 


39 


Cornns  circinata  L’Herit.  Koehler,  Conn. 

Cornus  amomurn  Mill.  Koehler,  Conn. 

Cornus  candidissima  Marsh . Koehler,  Conn. 

Cornus florida  Linn.  Commissioner  of  agriculture,  Felt,  N.  Y.;  Britton,  Conn. 
Cornus  florida.  Red  flowering.  Alwood,  Ya. 

Deutzia  sp.  Fernald,  Mass. 

Diospyros  virginiana  Linn.  Persimmon.  Lintner,  N.  Y. 

Elseagnus  sp.  Felt,  N.  Y. 

Elxagnus  longipes  Gray.  Silver  thorn.  Commissioner  of  agriculture,  N.  Y. ; Scott, 
Ga. 

Eucalyptus  sp.  Felt,  N.  Y. 

Euonymus  sp.  Lintner,  N.  Y. ; Alwood,  Ya. 

Ficus  carica  Linn.  Fig.  Felt,  N.  Y. 

Forsythia  sp.  Commissioner  of  agriculture,  N.  Y. 

Fraxinus  sp.  Ash.  Felt,  N.  Y. ; Butz,  Pa. 

Fraxinus  americana  Linn.  White  ash.  Hunter,  Kans. 

Gleditschia  triacanthos  Linn.  Honey  locust.  Britton,  Conn. ; Sanderson,  Del. ; com- 
missioner of  agriculture,  N.  Y. ; Johnson,  Md. 

Hibiscus  syriacus  Linn.  Shrubby  althea.  Smith,  N.  J. 

Hicoria pecan  Britt.  Pecan  nut.  Lintner,  N.  Y.;  Alwood,  Va. ; Scott,  Ga. 

Juglaus  nigra  Linn.  Black  walnut.  Alwood,  Va. ; Rolfs  & Quaintance,  Fla. 
Juglansregia  Linn.  Persian  or  English  walnut.  Alwood,  Va. ; Lintner,  Felt,  N.  Y.; 
Sanderson,  Md. 

Kalmia  latifolia  Linn.  Mountain  laurel.  Felt,  N.  Y. 

Kerria  japonica  DC.  Globe  flower.  Japanese  rose.  Felt,  N.  Y. 

Ligustrum  ovalifolium  Hassk.  California  privet.  Britton,  Koehler,  Conn. 

Lonicera  sp.  Honeysuckle.  Felt,  N.  Y. 

Morus  sp.  Mulberry.  Alwood,  Va. ; Burgess,  Ohio;  Johnson,  Md.;  Scott,  Ga. 
Morns  sp.  Tea’s  weeping  mulberry.  Taft,  Mich. 

Physocarpus  opulifolius  Maxim.  Koehler,  Conn. 

Picea  alba  Link.  White  spruce.  Fernald,  Mass. 

Prunus  cerasus  Linn.  Sour  cherry.  Felt,  N.  Y. ; Alwood,  Va. ; Burgess,  Ohio. 
Photinia  villosa  DC.  Koehler,  Conn. 

Rliodotypos  kerrioides  Sieb.  & Zucc.  Koehler,  Conn. 

Rhus  sp.  Sumac.  Rolfs  & Quaintance,  Fla.;  Alwood,  Va. ; Felt,  N.  Y. 

Rh us  cotinus  Linn.  Smoke  bush.  Commissioner  of  agriculture,  N.  Y. 

Robinia  sp.  Locust.  Sanderson,  Del.;  Burgess,  Webster,  Ohio;  Johnson,  Md. 
Rubus  strigosus  Michx.  Red  raspberry.  Alwood,  Va. ; Lintner,  Felt,  N.  Y.;  John- 
son, Md. 

Rubus  nigrobaccus  Bailey  (R.  villosus).  Common  blackberry.  Lintner,  Felt,  N.  Y. ; 
Johnson,  Md. 

Rubus  villosus  Ait.  (R.  Canadensis).  Dewberry.  Felt,  N.  Y. 

Sambucus  sp.  Elder.  Commissioner  of  agriculture,  N.  Y. ; Fernald,  Mass.;  Webster, 
Ohio. 

Sassafras  officinale  Nees.  Sassafras.  Sanderson,  Del. 

Sorbaria  sorbifolia  A.  Braun  ( Spirsea  sorbifolia  L. ).  Britton,  Conn. 

Spirxa  sp.  Britton,  Conn.;  Lintner,  Felt,  N.  Y. ; Alwood,  Va. 

Thuya  occidental is  Linn.  Arbor vitse.  Fernald,  Mass. 

Viburnum  sp.  Britton,  Conn.;  Alwood,  Va. 

Viburnum  cassinoides  Linn.  Britton,  Koehler,  Conn. 

Viburnum  opulus  Linn.  Koehler,  Conn. 

Vitis  sp.  Grapes.  Britton,  Conn.;  Felt,  N.  Y. ; Alwood,  Va. ; Butz,  Pa.;  Rolfs  & 
Quaintance,  Fla.;  Johnson,  Md. 


40 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


NOT  INFESTED. 

Ailanthus  glandulosa  Desf.  Tree  of  heaven. 

Amorpha  fruticosa  Linn. 

Andromeda  sp. 

Aralia  spinosa  Linn.  Hercules’  club. 

Aristolochia  macrophylla  Lain.  Dutchman’s  pipe. 

Asimina  triloba  Dun.  Papaw. 

Baccharis  halimifolia  Linn.  Groundsel  tree. 

Benzoin  odor iferum  Nees.  {Linder a benzoin  Blame).  Spicebush. 
Berber's  (all  species).  Barberry,  including  Mahonia. 

Bignonia  sp.  Trumpet  vine. 

Calycanthus  floridus  Linn.  Carolina  allspice,  sweet-scented  shrub. 
Carpinus  sp.  Hornbeam. 

Cedrus  sp.  Cedar. 

Celastrus  scandens  Linn.  Bittersweet. 

Cephalanthus  occidentals  Linn.  Buttonbush. 

Cercis  canadensis  Linn.  Judas  tree,  redbud. 

Chamxdaphne  calyculata  Moench.  ( Cassandra ).  Leather  leaf. 
Chionanthus  virginica  Linn.  Fringe  tree. 

Cladrastis  tinctoria  Raf.  Yellow  wood. 

Clethra  alnifolia  Linn.  Sweet  pepper  bush. 

Corylus  sp.  Filbert,  hazelnut. 

Daphne  mezereum  Linn. 

Diervilla  sp.  Weigela. 

Direct  palustris  Linn.  Leatherwood,  moosewood. 

Exochorda  grand, iflora  Lindl.  Pearlbush. 

Gaylussacia  sp.  Huckleberry. 

Genista,  tinctoria  Linn.  Dyer’s  greenweed. 

Ginkgo  biloba  Linn.  Maidenhair  tree. 

Gymnocladus  canadensis  Lam.  Kentucky  coffee  tree. 

Halesia  tetraptera  Linn.  Silver  bell,  snowdrop  tree. 

Hamamelis  virginiana  Linn.  Witch  hazel. 

Hedera  helix  Linn.  English  ivy. 

Hicoria  sp.  (excepting  H.  pecan  Britt).  Hickory. 

Hydrangea  (all  species). 

Hypericum  moserianum  Andre.  Gold  flower. 

Ilex  sp. 

Itea  virginica  Linn.  Virginian  willow. 

Jasminum  nudiflorum  Lindl.  Yellow  jasmine. 

Juglans  cinerea  Linn.  Butternut. 

Juniperus  sp.  Juniper. 

Kcelreuteria  paniculata  Laxm.  Varnish  tree. 

Laburnum  vulgare  Griseb.  Golden  chain. 

Larix  sp.  Larch. 

Liquidambar  styraciflua  Linn.  Sweet  gum. 

LAriodendron  tulipifera  Linn.  Tulip  tree. 

Lycium  halimifolium  Mill.  Matrimony  vine. 

Magnolia  (all  species). 

Myrica  cerifera  Linn.  Wax  myrtle. 

Nyssa  sylvaticct  Marsh.  Tupelo,  pepperidge,  black  gum,  sour  gum. 
Ostrya  virginica  Willd.  Hornbeam,  iron  wood. 

Paulownia  imperials  Sieb.  & Zucc. 


PLANTS  NOT  INFESTED* 


41 


Phellodendron  sp. 

Philadelphus  coronarius  Linn.  Mock  orange,  syringa. 

Pinus  sp.  Pine. 

Platanus  occidentalis  Linn.  American  plane,  buttonwood. 

Potentilla  fruticosa  Linn. 

Quercus  (all  species).  Oak. 

Retinispora  (all  species).  Japan  cypress. 

Rhamnus  sp.  Buckthorn. 

Rhododendron  sp. 

Sciadopitys  verticillata  Sieb.  & Zucc.  Umbrella  pine. 

Shepherdia  sp. 

Smilax  sp. 

Sophora  japonica  Linn.  Japan  pagoda  tree. 

Staphylea  sp.  Bladder  nut. 

Stephanandra  flexuosa  Sieb.  & Zucc. 

Styrax  japonica  Sieb.  & Zucc. 

Tamarix  sp. 

Taxodium  distichum  Rich.  Bald  cypress. 

Taxus  sp.  Yew. 

Tecoma  radicans  Juss.  Trumpet  creeper. 

Tsuga  canadensis  Carr.  Common  hemlock. 

Vaccinium  sp. 

Wistaria  sp. 

Xanthoceras  sorbifolia  Bunge. 

Xanthoxjylum  americanum  Mill.  Prickly  ash. 

Certain  species  have  been  reported  as  seriously  infested  in  one  part  of  the  country 
and  as  exempt  in  other  localities.  Such  plants  have  been  placed  in  list  No.  1. 
Quince  is  reported  as  being  rarely  infested,  by  .Felt,  of  New  York,  and  by  Smith,  of 
New  Jersey.  Sanderson  writes  that  willows  and  poplars  are  not  commonly  infested 
in  Maryland  and  Delaware,  but  in  Connecticut  willow  hedges  have,  been  seriously 
infested,  and  young  willow  and  poplar  trees  in  nurseries  have  been  thoroly  incrusted 
by  the  scales.  Cockerell  reports  that  osage  orange  is  not  infested  in  New  Mexico 
tho  much  grown,  and  that  Catalpa,  elm,  and  walnut  have  not  been  found  infested. 
Apricot,  quince,  and  poplar  are  also  reported  as  not  being  infested  in  New  Mexico. 
Alwood,  of  Virginia,  Burgess,  of  Ohio,  and  Felt,  of  New  York,  place  the  sour  cherry 
(P.  cerasus)  in  list  No.  2,  tho  I have  never  found  it  infested  in  Connecticut.  Burgess 
suggests  that  Kieffer  pear  be  placed  in  the  same  list,  but  it  is  reported  by  Alwood  as 
being  badly  infested  in  Virginia.  Linden  was  placed  in  list  No.  1 by  the  commis- 
sioner of  agriculture  of  New  York,  while  the  hop-tree  ( Ptelea  trifoliata)  was  placed 
in  the  same  list  by  Fernald  of  Massachusetts.  Elm  was  placed  in  list  No.  1 by 
Webster  in  Ohio  and  Troop  of  Indiana.  Smith,  of  New  Jersey,  finds  European  elm, 
purple-leaved  beech,  and  Japanese  walnut  badly  infested,  while  the  common  quince, 
cherry  (except  on  Japanese  stock),  apricot,  and  poplar  are  not  commonly  infested. 
He  has  not  seen  the  scale  on  birch,  linden,  persimmon,  Catalpa,  Acacia,  or  Buxus. 
Alwood,  of  Virginia,  puts  the  common  privet  (L.  vulgare ) in  list  No.  1,  while  Koehler, 
in  Connecticut, -mentions  it  as  one  of  the  plants  upon  which  he  has  not  found  the 
scale,  tho  growing  near  infested  plants.  Gossard,  of  Florida;  Scott  and  Fiske,  of 
Georgia,  report  Citrus  trifoliata  as  being  badly  infested,  while  Alwood,  of  Virginia, 
places  this  plant  in  list  No.  2.  C.  aurantium  the  common  orange,  is  rarely  infested, 
according  to  Gossard. 

In  Connecticut  the  most  commonly  infested  plants  are  apple,  pear,  peach,  Japan 
plum,  and  currant  among  the  fruits,  tho  sweet  cherry,  European  plum,  quince,  and 
gooseberry  are  sometimes  seriously  injured. 


42 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


The  most  commonly  infested  ornamentals  are  purple-leaved  plum,  Crataegus , Japa- 
nese quince,  mountain  ash,  red-twigged  dogwood,  and  Rosa  rugosa.  Poplar,  willow. 
Persian  lilac,  Cotoneaster,  elm  (both  American  and  European),  and  osage  orange 
have  been  found  thoroly  incrusted  by  the  insects,  especially  when  growing  neai 
infested  trees. 

Of  the  plants  which  are  reported  as  noninfested  in  this  list 
probably  many  of  them  may  be  subject  to  slight  or  occasional 
infestation.  Notwithstanding  the  San  Jose  scale’s  wide  range  of  food 
plants,  strangely  enough  certain  varieties  of  pear  seem  to  be  almosl 
never  attacked,  and  are  practically  exempt  from  injury.  This  hold:- 
true  also,  to  a less  extent,  with  different  varieties  of  other  fruits. 
The  striking  illustrations  are  the  Leconte  and  Kieffer  varieties  ol 
pears,  and  the  reason  for  this  immunity  is  difficult  to  explain.  Differ 
ences  in  the  density  and  texture  of  bark  could  hardly  account  for  it. 
because  that  would  scarcely  protect  new  and  comparatively  tendei 
growth.  A notable  instance  of  the  immunity  of  the  Leconte  pear  b 
seen  in  the  little  grove  connected  with  the  insectary  of  this  Depart 
ment.  This  grove  has  been  thickly  planted  to  pear  and  apple  trees,  s( 
that  the  branches  are  interlacing  all  the  time,  and  it  has  been  pretty 
badly  infested  with  the  San  Jose  scale  off  and  on  for  ten  }^ears,  anc 
yet  the  10  or  12  Leconte  trees  have  been  clean  the  whole  time,  whih 
the  rest,  representing  different  varieties  of  pear,  apple,  peach,  an( 
plum,  have  died  out  or  have  been  replaced,  some  of  them  over  anc 
over  again. 

CITRUS  FRUITS  AND  THE  SAN  JOSE  SCALE. 

The  susceptibility  of  the  orange  and  lemon  and  other  citrus  plant: 
to  the  San  Jose^cale  is  a matter  of  great  interest  to  citrus  growers 
In  catalogs  of  the  food  plants  of  the  San  Jose  scale  the  orange  an( 
lemon  and  other  citrus  fruits  are  listed,  notably  in  Mrs.  Fernald’; 
Catalog  of  Coccidae.  The  facts  on  which  this  statement  is  based  ar< 
rather  meager,  and,  when  examined,  do  not  warrant  any  grave  fear 
of  injury  to  the  ordinary  cultivated  citrus  fruits.  It  is  well  known 
that  the  San  Jose  scale  will  infest  rather  freely  the  trifoliate  orange 
a hedge  plant  somewhat  closely  related  to  the  orange  and  lemon 
Some  trifoliate  trees,  for  example,  on  the  Department  grounds,  ar 
now  rather  thickly  covered  by  the  San  Jose  scale,  but  even  in  the  cas« 
of  this  hedge  plant  the  infestation  is,  as  a rule,  not  serious,  andl 
according  to  Mr.  Gossard,  the  plant  seems  to  throw  the  scale  ofi  as  il 
grows.  The  first  undoubted  example  of  San  Jose  scale  on  orange  waj 
on  certain  hybrid  sorts  produced  by  crossing  the  trifoliate  orange! 
with  the  sweet  orange,  and  was  received  in  1903  from  Mr.  GossarM 
from  Florida.  Mr.  Gossard  stated  that  in  a single  instance  where  fljj 
small  sweet  orange  tree  interlaced  with  the„  branches  of  a badljj'1 
infested  trifoliate  orange  the  former  had  matured  perhaps  half  a doze# 
San  Jose  scales. 


LIFE  HISTORY. 


43 


The  second  undoubted  record  is  of  material  sent  to  Doctor  Howard 
or  determination  by  Dr.  James  Fletcher,  entomologist  of  the  Canadian 
Central  Experimental  Farm  at  Ottawa,  who  reported  that  the  infested 
ranges  sent  had  been  forwarded  to  him  from  British  Columbia  and  had 
>een  imported  from  Japan.  These  oranges,  evidently  of  a mandarin  or 
angerine  type,  showed  undoubted  infestation  with  the  San  Jose  scale. 

1 1 is  therefore  evident  that  this  scale  insect  ma}'  occasionally  infest 
he  orange,  but  the  long  coexistence  of  the  San  Jose  scale  and  orange 
ulture  in  southern  California  would  seem  to  indicate  the  practical 
mmunity  of  the  orange  tree  from  this  scale  pest.  An  earlier  record 

||»f  the  San  Jose  scale  on  a citrus  plant,  by  Mr.  Cockerell,  has  always 
>een  under  the  question  of  a misidentification  of  the  food  plant. 

LIFE  HISTORY. 

In  common  with  all  the  armored  scales,  the  life  round  of  this  insect, 
nth  the  exception  of  a few  hours  of  active  larval  existence  and  an 
squally  brief  winged  existence  in  the  case  of  the  mature  male,  is  past 
inder  the  protection  of  a waxy  scale.  This  scale  covering  conceals 
jhe  real  insect  beneath  and  prevents  any  easy  observation  or  study  of 
ts  life  history.  The  San  Jose  scale  has  been  under  most  careful 
•bservation  b}r  Mr.  Pergande  on  potted  plants  in  the  insectary,  and  its 
listory,  which  has  hitherto  been  very  imperfectly  worked  out,  has  been 
horoly  and  carefully  elaborated. 

The  winter  is  past  by  the  insects  in  a half-grown  condition  under 
mall  black  protecting  scales,  mere  points,  just  visible  to  the  naked 
ye.  The  male  scales  are  normally  vastly  in  excess  of  the  females, 
>ften  representing  95  or  more  per  cent.  Early  in  April,  in  this  lati- 
tude, the  males  transform  to  pupae  and  emerge,  and  this  gives  the 
.ppearance  of  .a  sudden  death  of  the  great  majority  of  these  overwin- 
ered  insects  on  the  bark,  and  has  led  to  some  confusion  in  interpret- 
ng  the  effect  of  washes.  The  females  at  this  period  have  arrived 
it  the  stage  of  impregnation,  and  the  delicate  two-winged  males  dis- 
ippear  after  a few  da}^s.  About  a month  later,  varying  with  the  cli- 
nate,  the  overwintered  females  come  to  full  maturity  and  begin  to 
pve  birth  to  a new  generation,  continuing  to  produce  young  for  a 
)eriod  of  upward  of  six  weeks,  when  they  reach  the  limit  of  produc- 
tion of  young  and  perish. 

The  adult  female  gives  birth  immediately  to  living  young,  differing 
n this  respect  from  most  other  scale  insects.  Ordinarily  eggs  are 
leposited  beneath  the  scale,  which  in  the  course  of  a longer  or  shorter 
ime  hatch,  and  the  young  larvae  make  their  escape  and  migrate  to 
lifferent  parts  of  the  plant.  In  the  case  of  some  scale  insects  the 
emale  fills  its  scale  with  eggs  in  the  fall  and  perishes,  the  eggs  win- 
ering over  and  hatching  the  following  spring.  In  others  the  insect 


44 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


hibernates  in  the  nearly  mature  condition,  as  does  the  San  Jose  scale, 
and  deposits  eggs  in  the  spring  or  early  summer.  The  viviparous  ' 
habit,  or  the  giving  birth  to  the  living  young,  possest  by  the  San  Jose 
scale,  finds  a parallel  in  many  other  insects  and  frequently  in  aphides. 
In  the  case  of  the  San  Jose  scale  the  eggs  are  fairly  well  formed, 
a few  at  a time,  within  the  bod}^  of  the  mother.  What  takes  the  place 
of  the  eggshell  consists  of  a very  delicate  and  thin  membrane — the 
amnion — which  incloses  the  developing  larva  and  which  at  the  moment 
of  birth  is  cast  off,  and  remains  attached  to  or  partly  within  the  ovi- 
duct. The  amnion  is  probably  pushed  out  b}T  the  next  larva  in  turn. 


Fig.  3.— Young  larva  and  developing  San  Jose  scale  ( Aspidiotus  perniciosus):  a,  ventral  view  of 
larva,  showing  sucking  beak  with  setae  separated,  with  enlarged  tarsal  claw  at  right;  b,  dorsal  view 
of  same,  still  more  contracted,  with  the  first  waxy  filamentsappearing;  c,  dorsal  and  lateral  views 
of  same,  somewhat  contracted,  illustrating  further  development  of  wax  secretion;  d,  later  stage  of 
same,  dorsal  and  lateral  views,  showing  matting  of  wax  secretions  and  first  form  of  young  scale. 
All  greatly  enlarged  (from  Howard  and  Marlatt). 

The  difference  between  this  mode  of  birth  and  the  ordinary  method 
thru  the  medium  of  true  eggs  is  simply  that  what  corresponds  with 
the  egg  is  retained  by  the  female  until  the  larva  is  developed,  instead 
of  development  of  the  larva  progressing  after  the  egg  leaves  the 
parent. 

The  emergence  of  the  young  from  the  female  over  a period  of  six 
weeks  leads  to  a very  confusing  intermingling  of  generations  and 
renders  it  difficult  to  make  observations  on  the  life  history  except  by 
isolating  and  watching  individuals.  By  means  of  such  isolation  of 
individuals,  however,  we  have  been  able  to  most  carefully  trace  the 


LIFE  HISTORY. 


45 


lifferent  generations.  The  course  of  the  development  of  a single 
generation  follows: 

| After  being  expelled  the  larva  remains  motionless  for  a little  while, 
with  antennae  and  legs  folded  beneath  the  body.  It  soon  hardens 
mough  to  run  about,  and,  forcing  its  way  out  from  beneath  the  pro- 
jecting scale  of  the  mother,  scurries  over  the  plant  to  find  a suitable 
blace  to  settle. 

The  newly  born  larva  (fig.  3,  a)  is  an  almost  microscopic  creature  of 
pale  orange-yellow  color,  with  long  oval  body,  and  with  the  customary 
;ix  legs  and  two  feelers.  The  long  thread-like  proboscis  with  which 
?;he  juices  of  the  plant  are  sucked  up  is  doubled  on  itself  and  lies  in  an 
nvagination  of  the  body  wall,  the  tip  only  projecting. 

After  crawling  about  for  a few  hours  the  young  larva  settles  down 
ind  slowly  works  its  long  bristle-like  sucking  beak  thru  the  bark, 
bids  its  antennse  and  legs  beneath  its  body,  and  contracts  to  a nearly 
‘ircular  form.  The  development  of  the  scale  begins  even  before  the 
arva  becomes  fixt.  The  secretion  starts  in  the  form  of  very  minute 
white  fibrous  waxy  filaments,  which  spring  from  all  parts  of  the  body 
tnd  rapidly  become  more  numerous  and  dense  (fig.  3,  5,  c).  At  first  the 
orange  color  of  the  larva  shows  thru  the  thickening  downy  white 
envelop,  but  within  two  days  the  insect  becomes  entirely  concealed  by 
he  white  or  pale  grayish  yellow  shell  or  scale,  which  now  has  a promi- 
nent central  nipple  (fig.  3,  d ),  the  younger  ones  often  possessing  instead 
i central  tuft.  The  scale  is  formed  by  the  slow  matting  and  melting 
together  of  the  filaments  of  wax.  During  the  first  day  the  scale  appears 
ike  a very  microscopic  downy  hemisphere.  The  matting  of  the  secre- 
tion continues  until  the  appearance  of  down  and  individual  filaments  is 
entirely  lost  and  the  surface  becomes  smooth.  In  the  early  history  of 
be  scale  it  maintains  its  pale  whitish  or  grayish  yellow  color,  turning 
gradually  darker  gray,  the  central  nipple  remaining  lighter  colored 
isually  thruout  development. 

The  male  and  female  scales  are  exactly  similar  in  size,  color,  and  shape 
intil  after  the  first  molt,  which  occurs  twelve  days  after  the  emergence 
;>f  the  larva.  With  this  molt,  however,  the  insects  beneath  the  scale 
jose  all  resemblance  to  each  other.  The  males  (fig.  4,  a)  are  rather  larger 
ban  the  females  and  have  large  purple  eyes,  while  the  females  have  lost 
beir  eyes  entirety.  The  legs  and  antenna?  have  disappeared  in  both 
pexes.  The  males  are  elongate  and  pyriform,  while  the  females  are 
ilmost  circular,  amounting  practically  to  a flattened  sac  with  indistinct 
segmentation,  and  without  organs,  except  a long  sucking  bristle 
springing  from  near  the  center  beneath.  The  color  of  both  sexes  is  light 
emon -yellow.  The  scales  at  this  time  have  a decidedly  grayish  tint, 
>vercast  somewhat  with  yellow. 

Eighteen  days  from  birth  the  males  change  to  the  first  pupal  condi - 
:ion  (pro-pupa)  (fig.  4,  &),  and  the  male  scales  assume  an  elongate  oval, 


46 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


sometimes  slightly  curved,  shape,  characteristic  of  the  sex,  the  exuvia 
or  cast  larval  skin  showing  near  the  anterior  end. 

The  male  pro-pupae  are  very  pale  }^ellow,  with  the  legs  and  antennae 
(which  have  reappeared),  together  with  the  two  or  three  terminal  seg- 
ments, colorless.  The  eyes  are  dark  purple  and  placed  close  together. 
The  antennae  are  stout  and  bent  closely  along  the  edge  of  the  body  as 
far  as  the  first  pair  of  legs,  where  they  curve  slightly  inward.  Promi- 
nent wing  pads  extend  along  the  sides  of  the  body.  The  terminal 
segment  bears  two  short  spines. 

The  female  undegroes  a second  molt  about  twenty  days  from  the 
larva.  At  each  molt  the  old  skin  splits  around  the  edge  of  the  body! 
the  upper  half  adhering  to  the  covering  scale  and  the  lower  forming  a 
sort  of  ventral  scale  next  to  the  bark.  This  form  of  molting  is  com- 
mon to  scales  of  this  kind. 


Fig.  4. — Development  of  male  San  Jose  scale  {Aspidiotus  perniciosus):  a,  ventral  view  of  larva  after 
first  molt;  b,  same  after  second  molt  (pro-pupa  stage);  c and  d,  true  pupa,  ventral  and  dorsal  views. 
All  greatly  enlarged  (from  Howard  and  Marla tt). 


The  covering  scales  at  this  stage  are  of  a more  purplish  gray,  the 
portion  covering  the  exuviae  inclining  to  yellowish.  The  male  scales 
are  more  yellowish  than  the  female.  The  effect  of  the  sucking  of  the 
insects  is  now  quite  apparent  on  the  young  growth,  causing  the  bark 
to  assume  a purplish  hue  for  some  distance  around  the  central  portion, 
contrasting  strong^  with  the  natural  reddish  green  of  the  uninjured 
bark.  With  the  second  molt  the  females  do  not  change  materially 
from  their  former  appearance,  retaining  the  pale  yellow  color  with  a 
number  of  transparent  spots  around  the  edge  of  the  body.  The  suck- 
ing bristles  are  extremely  long,  two  or  three  times  the  length  of  the 
body  of  the  insect.  The  only  distinctive  features  are  in  the  last  seg- 
ment and  are  noted  in  the  technical  description. 

About  twenty  days  after  birth  the  male  insect  transforms  to  the 
true  pupa.  With  the  first  molt  the  shed  larval  skin  is  retained  beneath 
the  scale  as  in  the  case  of  the  female;  with  the  later  moltings  the  shed 
skins  are  pushed  out  from  beneath  the  scale.  The  scale  after  the 


LIFE  HISTORY. 


47 


second  molt  presents  on  the  inside  two  longitudinal  ridges  running 
from  one  end  to  the  other,  touching  the  sides  of  the  pupa,  and  which 
apparently  enable  the  insect  to  move  backward  or  forward  and  assist 
the  imago  in  pushing  itself  out. 

The  true  pupa  (fig.  4,  c,  d)  is  pale  yellow,  sometimes  purplish,  darkest 
about  the  base  of  the  abdomen.  The  head,  antenme,  legs,  wing  pads, 
and  style  are  well  formed,  but  almost  colorless.  The  antennae  reach 
as  far  back  as  the  second  pair  of  legs  and  are  not  curved  under,  as 
formerly,  but  lie  close  to  the  sides  of  the  body  with  the  ends  free. 
The  first  pair  of  legs  is  held  forward,  reaching  slightly  beyond  the 
eyes,  the  middle  femora  projecting  somewhat  beyond  the  margin  of 
S the  abdomen.  The  hind  legs  are  inclined  backward  and  reach  to  the 
end  of  the  body.  The  style  is  rounded  at  tip,  conical,  and  about  as 
long  as  the  posterior  tibiae. 


Fig.  5. — Aspidiotus  perniciosus:  adult  male,  greatly  enlarged  (from  Howard  and  Marlatt). 

From  four  to  six  days  later,  or  from  twenty-four  to  twent3"-six  da}^s 
from  birth,  the  males  mature  and  back  out  from  the  rear  end  of  their 
scales,  having  previously,  for  a day  or  two,  remained  practically 
developed  but  resting  under  the  scale.  They  seem  to  issue  chiefly  b}^ 
night  or  in  the  evening. 

The  mature  male  (fig.  5)  appears  as  a delicate  two-winged  fly-like 
insect  with  long  feelers  and  a single  anal  style  projecting  from  the  end 
of  the  body;  orange  in  color,  with  a faintly  dusky  shade  on  the  pro- 
thorax. The  head  is  darker  than  the  rest  of  the  body,  the  eyes  are 
dark  purple,  and  the  antennae,  legs,  and  style  are  smoky.  The  wings 
are  iridescent  with  yellow  and  green,  very  faintly  clouded. 

Thirty  days  from  birth  the  females  are  full  grown  and  the  embryonic 
young  may  be  seen  within  their  bodies,  each  inclosed  in  a delicate 
8449— No.  62—06 4 


48 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


membrane.  At  from  thirty-three  to  forty  days  the  larva?  again  begin 
to  make  their  appearance. 

The  adult  female,  prior  to  the  developments  the  young,  measures  1 
millimeter  in  length  and  a little  less  in  breadth,  and  is  pale  yellow,  with 
transparent  spots  near  the  margin  of  the  body  (fig.  6). 

The  length  of  a generation  is  determined  by  the  female  and,  as 
shown  by  the  above  record,  covers  a period  of  from  thirty- three  to 
forty  days.  Successive  generations  were  followed  carefully  thruout 


Fig.  6.— Adult  female  San  Jose  scale  {Aspidiotus  perniciosus)  before  development  of  eggs:  a,  ventral 
view,  showing  very  long  sucking  setae;  b,  anal  plate,  showing  characteristic  ornamentation  of  edge. 
Greatly  enlarged  (from  Howard  and  Marlatt). 


the  summer,  and  it  was  found  that  at  Washington  four  full  generations 
are  regularly  developed,  with  the  possibility  of  a partial  fifth  genera- 
tion. On  a number  of  potted  trees  a single  overwintered  female  was 
left  to  each  tree.  After  the  full  progeny  of  this  individual  had  gone 
out  over  the  tree,  all  were  removed  again,  except  one  of  the  oldest  and 
fertilized  females.  This  method  was  continued  for  each  generation 
thruout  the  breeding  season.  Some  interesting  records,  tabulated 
below,  were  thus  obtained,  which  indicate  the  fecundity  of  the  females 
as  well  as  the  number  of  generations. 


LIFE  HISTORY. 


49 


Record  showing  fecundity  of  San  Jose  scale. 


Number  of  tree. 

Males. 

Females. 

Total. 

Number  of  tree. 

Males. 

Females. 

Total. 

Pvogen 

1 

j of  overwintered 

Progen: 

I 

y of  third  genera- 

females. 

tion. 

1 

72 

34 

106 

1 

110 

307 

417 

2 

77 

43 

120 

2 

122 

464 

586 

3 

138 

60 

198 

3 

190 

284 

474 

4 

18 

22 

• 40 

4 

187 

400 

■ 587 

5 

98 

60 

158 

5 

174 

280 

454 

6 

33 

25 

58 

6 

107 

274 

354 

13 

13 

Progen, 

y of  fourth 

genera- 

Progen, 

j of  secona 

l gener- 

tion. 

ation. 

1 

242 

319 

561 

1 

350 

235 

585 

2 

112 

230 

342 

2 

276 

226 

502 

92 

170 

262 

3 

325 

92 

417 

4 

210 

344 

554 

4 

192 

120 

312 

1 5 

242 

343 

585 

5 

415 

151 

556 

6 

156 

293 

449 

206 

124 

330 

Perhaps  the  most  notable  feature  of  the  foregoing  records  is  the 
result  obtained  from  the  overwintered  females.  It  will  be  seen  that 
the  males  greatly  predominate  in  this  generation,  and  that  the  numbers 
of  both  sexes  are  insignificant  compared  with  the  progeny  of  the  later 
generations.  The  males  still  predominate  in  the  second  generation, 
but  in  the  third  and  fourth  generations  the  females  considerably  out- 
number the  males,  in  one  instance  the  females  from  a single  mother 
reaching  the  astonishing  number  of  464,  which,  with  122  males  from 
the  same  parent,  makes  the  progeny  of  this  female  586  insects.  Tak- 
ing 200  females  as  an  average  of  the  different  generations  for  the 
year,  the  product  of  a single  individual  from  spring  to  fall  amounts  to 
1,608,040,200  females.  In  one  instance  we  have  over  415  males  from 
a single  female,  and  while  the  number  of  males  would  average  some- 
what less  than  the  females,  taking  the  summer  thru,  yet,  having 
underestimated  the  females,  the  males  may  be  estimated  at  the  same 
number,  giving  a total  of  3,216,080,400  descendants  from  a single 
insect  in  a single  season.  It  is  not  to  be  expected,  of  course,  that  all 
the  individuals  from  a scale  survive  and  perform  their  function  in  life, 
but  under  favorable  conditions,  or  in  the  case  of  a tree  newly  infested 
or  not  heavily  incrusted,  th6  vast  majority  undoubtedly  go  thru  their 
existence  without  accident.  Neither  the  rapidity  with  which  trees 
become  infested  nor  the  fatal  effect  which  so  early  follows  the  appear- 
ance of  this  scale  insect  is  therefore  to  be  wondered  at. 

Owing  to  the  long  period  during  which  the  female  is  continuously 
producing  young  the  different  generations  or  broods  in  the  course  of  the 
summer  are  not  distinctl}7  marked  and  merge  insensibly  into  each  other — 
so  much  so  that  at  almost  any  time  there  will  be  found  young  larvse 
running  about  over  the  trees  and  scales  in  all  stages  of  development. 
Still,  at  certain  times  the  young  will  be  noticeably  more  abundant, 
indicating  periods  when  the  majority  of  each  generation  are  producing 
young.  In  this  latitude  the  first  young  appear,  as  noted,  by  the  middle 


50 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


of  May;  at  Amherst,  Mass.,  they  were  first  noticed  June  12,  and  in 
Arizona  they  are  recorded  as  appearing’  in  March.  The  larvye  are  con- 
tinuously present  on  the  trees  until  further  hatching  is  prevented  by 
severe  frosts.  In  1894,  as  we  have  already  shown  on  page  289  of  Vol- 
ume VII  of  Insect  Life,  the  first  frosts  at  Washington  occurred  in  the^ 
latter  part  of  October  and  the  hatching  of  the  young  ceased  before  the 
1st  of  November.  October  24,  1894,  however,  Doctor  Howard  saw 
recently  settled  larvae,  not  more  than  5 days  old,  at  Lewisburg,  Pa.  In 
1895  the  October  frosts  were  insignificant,  and  in  this  neighborhood 
no  severe  frost  occurred  until  about  the  1st  of  December.  The  result 
was  that  young  larvae  were  found  at  Washington  until  late  in  Novem- 
ber, while  on  twigs  received  from  Chestertown,  Md.,  November  13  and 
November  27,  the  young  were  more  or  less  abundant.  The  cold  spell 
of  the  last  week  in  November  and  the  first  week  in  December  put  a 
stop  to  development  here.  This  same  cold  spell  was  of  ver}-  wide 
extent.  As  far  to  the  southwest  as  San  Antonio,  Tex.,  the  thermom- 
eter dropped  to  31°  on  December  3.  A similar,  or  even  lower,  tem- 
perature was  noted  at  New  Orleans,  yet  on  December  16  Doctor 
Howard  found  newly  hatched  young,  less  than  24  hours  old,  upon  a 
plum  tree  at  Audubon  Park,  New  Orleans. 

In  autumn,  or  when  further  development  is  stopt  by  cold  weather, 
hibernation  is  begun  by  scales  in  all  stages  of  development,  from  the 
white,  minute,  down-covered  recently  hatched  young  to  the  mature  and 
full-grown  females  and  males.  Unquestionably  many  young  perish 
during  the  winter,  and  normally  in  spring  quite  a percentage  of  the 
smaller  or  half -grown  scales  will  be  found  to  have  perished.  It  is 
very  probable  that  many  females  have  union  with  the  males  in  the  fall, 
but  the  majority  of  them  are  unquestionably  immature,  and  are  fertil- 
ized in  this  latitude  early  in  April  by  overwintered  males  which,  as  we 
have  noted,  appear  nearly  a month  before  the  first  young  of  the  spring 
brood. 

The  actual  rate  of  the  production  of  young  at  different  periods  of 
the  life  of  the  adult  female  has  not  been  determined  with  accuracy. 
As  the  average  reproducing  period  of  the  'adult  female  is  six  weeks, 
and  as  the  average  number  of  young  from  each  female  is  about  400, 
there,  must  be  born  from  9 to  10  young  every  twenty-four  hours.  The 
great  labor  of  watching  an  individual  female  and  removing  every 
twenty-four  hours  the  young  she  has  given  birth  to  during  that  period 
has  not  been  entered  upon.  Sufficient  observations  have  been  made, 
however,  to  indicate  that  the  main  period  of  reproductive  activity  is 
the  second  or  third  week  after  the  female  has  reached  maturity.  At 
first  the  young  arc  born  with  less  frequency,  and  there  is  a correspond- 
ing reduction  in  reproductive  activity  toward  the  end  of  the  life  of  the 
individual.  The  young  are  born  indifferently  by  day  or  by  night,  per- 
haps more  during  the  day  than  during  the  night.  In  the  morning, 


DESCRIPTIONS  OF  SCALE  AND  INSECT. 


51 


however,  examination  of  the  trees  under  observation  always  shows 
manv  migrating  young  which  must  have  been  born  during  the  night, 
while  observations  at  nightfall  show  always  as  many,  and  frequently 
more,  which  have  been  born  during  the  day. 

The  gradual  production  of  the  young  by  the  female  has  an  important 
bearing  on  the  question  of  remedies,  and  the  old  washes,  which  aimed 
at  the  destruction  of  the  young  as  soon  as  they  emerge  from  the  females, 
are  rendered  almost  valueless  because,  to  make  them  effective,  it  is 
necessary  to  repeat  them  many  times  during  a period  of  six  weeks. 
Within  two  or  three  days  after  hatching  the  young  larva?  will  have 
formed  a scale  which  will  be  impervious  to  these  weaker  washes. 

The  larva  does  not  ordinarily  travel  far  from  the  parent  insect,  and 
usually  rests  within  a few  inches  of  the  old  scale  or  at  the  first  avail- 
able point.  They  will  not,  so  far  as  observed,  travel  very  far  from 
the  base  of  the  tree,  and  in  the  potted  trees  none  were  observed  to  go. 
more  than  2 inches  from  the  base  of  the  trunk. 

DESCRIPTIONS  OF  SCALE  AND  INSECT. 

Scale  of  female. — The  scale  of  the  female  is  circular,  very  slightly 
raised  centrally,  and  varies  in  diameter  from  1 to  2mm,  averaging  about 
1.4mm.  The  exuvia  is  central  or  nearly  so.  The  large,  well-developed 
scales  are  gray,  excepting  the  central  part  covering  the  exuvia,  which 
varies  from  pale  to  reddish  yellow,  altho  in  some  cases  dark  colored. 
The  scale  is  usually  smooth  exteriorly  or  sometimes  slightly  annulated, 
and  the  limits  of  the  larval  scale  are  always  plainly  marked.  The 
natural  color  of  the  scale  is  frequently  obscured  by  the  presence  of 
the  sooty  fungus  ( Fumago  salicina). 

Scale  of  male. — The  mature  male  scale  is  oblong-oval,  nearly  twice  as 
long  as  wide,  and  averaging  in  length  about  half  the  diameter  of  the 
female  scale.  The  position  of  the  larval  scale  is  marked  by  a nipple- 
like prominence  located  between  the  center  and  the  anterior  margin 
of  the  scale.  The  scale  of  the  male  is  usually  darker  than  that  of  the 
female,  sometimes  black,  but  often  gray,  the  larval  scale  covering  the 
exuvia  very  frequentty  light  yellow,  as  with  the  female.  Not  uncom- 
monly the  circular  scale,  formed  prior  to  the  first  molt,  is  black,  while 
the  later  additions,  giving  it  its  oblong  shape,  are  gray. 

The  scale  covering  of  the  hibernating  insects  in  winter  is  black,  and 
on  the  bark  in  summer  also  the  scple  covering  is  dark  or  often  black- 
ened by  the  sooty  fungus  referred  to.  But  the  normal  color  of  the 
scale  of  both  female  and  male  is  light,  and  on  the  leaves  of  pear,  for 
example,  the  male  scales  are  often  a very  light  buff,  and  present  such 
a marked  contrast  to  the  winter  appearance  that  no  one  would  suspect 
them  of  belonging  to  the  same  insect. 

Egg. — The  egg  is  never  (or  rarely)  extruded  as  such  by  the  female, 
and  as  it  exists  within  the  body  of  the  mother  is  a mere  amniotic  mem- 


52 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


brane,  and  the  forming  embryo  showing  through  gives  it  a yellowish- 
white  color.  The  embryo  with  the  envelop  measures  about  0.2mm  long 
by  ().lmra  wide. 

Newly  hatched  larva. — The  y oung  larvae  of  both  sexes  are  alike,  and 
are  pale  orange  in  color,  with  long  oval  bodies.  They  measure  in  length 
about  0.24mm  by  0.1mm  in  width.  The  sucking  bristles  are  normally? 
doubled  on  themselves,  but  when  unfolded  are  nearly  three  times  the  : 
length  of  the  body.  The  antennae  are  apparently  five-jointed,  the  last] 
two  joints  being  much  longer  than  the  others,  slender,  subequal  in 
length,  and  both  finely  and  distinctly  annulated.  The  last  joint  bears  ] 
a small  nipple-like  projection  near  the  tip.  The  head  is  somewhat  con- 
cave in  front,  and  the  eyes  are  nearly  transparent  and  slightly  purplish. 
The  terminal  segment  of  the  abdomen  foreshadows  in  structure  the  i 
plates  and  spines  of  the  adult  female.  The  large  central  plates  each 
terminate  in  a long  hair.  The  tarsus  is  represented  by  apparently  a 
single,  strong,  slightly  curved  claw.  The  tip  of  the  tibia  bears  exteri- 
orly two  rather  long  capitate  hairs,  and  two  similar  hairs  project  also 
from  the  inner  extremity.  Other  details  of  structure  are  shown  in  the 
illustration. 

Larva  of  the  second  stage. — After  the  first  molt  the  difference  in  the 
sexes  becomes  apparent,  altho  the  covering  scales  are  still  identical. 

The  female  insects  are  somewhat  smaller  than  the  males  at  this  stage. 
The  e}Tes,  legs,  and  antennae  in  this  sex  have  entirely  disappeared.  The 
form  is  almost  circular,  flattened.  The  eolor  is  }7ellow,  with  irregular 
transparent  spots  appearing  in  different  parts  of  the  body. 

The  males  are  somewhat  larger  than  the  females,  elongate,  pyriform. 
The  eyes  are  prominent,  purple  in  color.  The  legs  and  antennae,  as 
with  the  females,  are  wanting.  The  general  color  of  the  body  is 
yellow,  with  the  irregular  transparent  spots  noted  in  the  case  of  the 
female.  The  greatest  diameter  in  both  sexes  is  less  than  one-half  a 
millimeter,  and  in  the  characteristics  of  the  terminal  segment  both 
agree,  practically,  with  the  adult  female. 

Male  pro-pupa. — With  the  second  molt  the  male  assumes  a form 
foreshadowing  the  true  pupa,  which  may  be  called  the  pro-pupa. a 
The  form  is  elongate  oval;  length  0.5mm.  The  color  is  very  pale 
yellow,  with  the  antenna3,  limbs,  and  wingpads,  and  two  or  three  ter- 
minal segments  of  the  abdomen,  colorless.  The  legs  and  antennae,  as 
noted,  have  reappeared,  and  also  prominent  pads  foreshadowing  the 
wings  of  the  adult.  The  eyes  are  dark  purple  and  placed  close  together. 
The  antennae  are  very  stout,  and  curved  closely  around  the  edge  of 
the  bod}7  as  far  as  the  anterior  legs,  where  they  bend  inward.  The  i 

« The  existence  of  a pro-pupa  or  a first  pupal  stage  in  the  CoccicUe  analogous  to  fl 
the  first  pupal  stage  of  higher  Hemiptera  has  also  been  affirmed  by  Dr.  Fr.  Loew.  J 
(Wiener  Entom.  Zeit.,  Jan.,  1884,  p.  13.) 


DESCRIPTIONS  OF  INSECT. 


53 


wing-pads  are  stout  and  almost  entirely  cover  the  abdomen.  The  ter- 
minal segment  is  still  broad  and  flattened  and  bears  two  short  spines, 
but  the  other  characters  have  disappeared. 

True  pupa  of  male. — The  true  pupa  resembles  the  previous  stage, 
except  that  the  members  are  longer  and  slenderer,  and  the  prominent 
anal  style  has  appeared.  The  pupa  is  pale  yellow  and  purplish  in 
color,  darkest  about  the  base  of  the  abdomen,  the  head,  antennae,  legs, 
wing  sheaths,  and  style  being  almost  colorless  and  transparent.  The 
eye  spots  are  dark  purple.  The  antennae  extend  nearly  to  the  middle 
femora,  and  are  not  curved  under  the  body jus  formerly,  but  are  applied 
close  to  the  sides  with  the  apex  free.  The  anterior  legs  are  held  for- 
ward, reaching  slightly  beyond  the  eyes.  The  middle  femora  rest 
transversely  to  the  body,  projecting  somewhat  beyond  the  margin  of 
the  abdomen,  while  their  tibiae  form  with  them  a light  angle  and  reach 
nearly  to  the  apex  of  the  hind  femora.  The  latter  incline  posteriorly, 
while  the  hind  tibiae  are  applied  close  to  the  sides  of  the  body,  except 
toward  the  tip,  and  reach  nearly  to  the  base  of  the  style.  The  style  is 
rather  stout,  conical,  obtusely  pointed  at  tip,  and  about  as  long  as 
posterior  tibiae.  Length,  0.8mm,  including  st}Tle,  which  measures  about 
0.15mra. 

Mature  male. — The  general  color  is  orange  with  a faint  duskiness  on 
the  prothorax.  The  head  is  somewhat  darker  than  the  rest  of  the 
body.  The  eyes  are  dark  purple,  almost  black.  The  antennae  are 
yellow,  somewhat  obscure  or  smoky.  The  legs  and  style  are  dusky, 
the  latter  paler  than  the  former.  The  thoracic  shield  is  regular^ 
ovoid,  compressed  anteriorty,  dusky  in  color,  with  margin  brown,  more 
distinctly  so  anteriorly;  transverse  band  narrow,  brown.  Antennae 
10-jointed,  two  basal  joints  shortest,  second  nearly  globular,  inserted 
in  the  first;  joints  4 and  5 subequal,  longer  than  any  of  the  others; 
joint  6 next  in  length,  and  joints  3,  7,  and  9 shorter  and  subequal; 
joint  10  still  shorter,  conical.  Antennae  somewhat  hairy  and  nearly  as 
long  as  the  body  of  the  insect.  Wings  faintly  dusky,  iridescent  with 
yellow  and  green.  Length  of  body  about  0.6ram;  style,  0.25mm. 

Female , third  stage. — After  the  second  molt  the  females  still  appear 
pale  yellow  as  before,  with  various  larger  and  smaller  transparent  spots 
around  the  border  of  the  body.  The  form  is  nearly  circular,  with 
greatest  diameter  averaging  0.56mm.  The  sucking  bristles  are  very 
prominent  and  long,  three  times  the  length  of  the  insect.  The  last 
segment  in  this  stage  has  practically  the  characters  of  the  mature  female, 
as  follows:  There  are  two  pairs  of  lobes,  the  terminal  ones  largest  and 
nearty  three  times  as  broad  as  the  other  lobes.  Terminal  lobes  are 
rounded  at  the  apex  and  are. distinctly  notched  near  the  middle  of  the 
external  edge.  The  second  pair  of  lobes  is  smaller  and  narrower,  and 
is  also  notched  externally.  Between  the  first  and  second  lobe  on  either 


54 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


side  is  a small  spine,  and  two  or  three  such  spines  are  just  back  of  the 
second  lobe,  while  back  of  these  are  three  stout  teeth  curving  anteri- 
orly. A still  smaller  blunt  tooth  sometimes  occurs  near  the  middle  of 
the  lateral  margin.  The  segmentation  of  the  body  at  this  stage  is  ' 
quite  distinct. 

Mature  female.—  After  reaching  maturity  the  embryonic  young  are 
at  first  not  visible,  but  later  the  body  becomes  filled  with  them.  The 
mature  female  measures  0.8mm  wide  by  about  lmm  long.a 

The  following  description  of  this  stage  is  reproduced  from  Comstock: 

The  body  of  the  female  is  yellowish  and  almost  circular  in  outline;  the  segmenta- 
tion is  distinct,  tho  not  conspicuous.  The  last  segment  presents  the  following 
characters : 

There  are  only  two  pairs  of  lobes  visible;  the  first  pair  converge  at  tip,  are  notched 
about  midway  their  length  on  the  lateral  margin,  and  often  bear  a slight  notch  on 
the  mesal  margin,  near  the  tip.  The  second  pair  are  notched  once  on  the  lateral  j 
margin. 

The  margin  of  the  ventral  surface  of  the  segment  is  deeply  incised  twice  on  each 
side  of  the  meson,  once  between  the  bases  of  the  first  and  second  lobes,  and  again 
laterad  of  the  second  lobe.  On  each  side  of  each  of  these  incisions  is  a club-shaped 
thickening  of  the  body  wall. 

There  are  two  inconspicuous  simple  plates  between  the  median  lobes,  and  on  each 
side  similar  plates  extending  caudad  of  the  first  incision,  three  small  plates  serrate 
on  their  lateral  margin  caudad  of  the  second  incision,  and  the  club-shaped  thicken- 
ings of  the  body  wall  bounding  it,  and  three  wide  prolongations  of  the  margin 
between  the  third  and  fourth  spines.  These  prolongations  are  usually  fringed  on 
their  distal  margins.  There  are  also,  in  some,  irregular  prolongations  of  the  margin 
between  the  fourth  spine  and  the  penultimate  segment. 

The  first  and  second  spines  are  situated  laterad  of  the  first  and  second  lobes, 
respectively;  the  third  spine  laterad  of  second  incision,  and  the  fourth  spine  about 
one-half  the  distance  from  the  first  lobe  to  the  penultimate  segment. 

SYSTEMATIC  POSITION  AND  RELATIONSHIPS. 

The  San  Jose  scale  was  described  by  Professor  Comstock  from 
material  collected  in  1880  in  Santa  Clara  County,  Cal.,  on  apple,  pear, 
plum,  and  other  fruit  trees.6  The  relationships  of  this  scale  insect 
have  been  discust  by  various  authors,  notably  by  Prof.  T.  D.  A.  Cock-  j 
erell,  without,  however,  reaching  a very  good  solution,  in  the  judg-  | 
ment  of  the  writer.  Without  going  into  a detailed  technical  discus-  | 
sion,  the  San  Jose  scale  is  quite  as  closely  allied  in  structure,  scale 
covering,  and  habit  with  the  Aonidiella  group  as  it  is  with  the  group  1 
including  ancylus  and  ostr'eseformis.  It  is  a very  distinct  and  well-  \ 
marked  species,  howTever,  and  is  alwaj^s  easy  of  identification  after  one  j 
becomes  once  familiar  with  its  principal  characteristic  structural  fea- 

tures,  and  it  is  one  of  the  few  scale  insects  which  can  ordinarily  be 

■ 

a Rept.  U.  S.  Dept.  Agric.,  1880,  p.  804. 

h Report  of  the  Entomologist,  in  the  Report  of  Commissioner  of  Agriculture  for 
1880  (1881),  pp.  304,  305. 


SYSTEMATIC  POSITION  AND  RELATIONSHIPS. 


safely  identified  from  the  appearance  of  the  scale  covering  and  with- 
out being  prepared  for  microscopical  study. 

Three  varieties  of  the  San  Jose  scale  have  been  designated,  none  of 
which  are  valid.  Of  these  Aspidiotus  perniciosus  var.  albopunctatus 
Ckll.  was  described  from  twigs  of  a supposed  orange  seedling  sent 
from  Japan  and  stopt  by  Mr.  Craw  in  his  quarantine  woik  in  San 
Francisco.  The  twigs  are  thorny  and  may  possibly  be  of  the  trifoliate 
orange  or  of  some  orange  seedling,  but  whether  of  ordinary  orange 
or  tangerine  or  some  other  horticultural  variety  can  not  be  determined. 
From  the  extreme  unlikelihood  of  the  San  Jose  scale  attacking  ordi- 
nary orange,  the  probability  is  very  strong  that  these  seedlings  were 
either  trifoliate  or  of  the  mandarin  or  tangerine  tj  pes.  At  any  rate, 
the  scale  itself  is  typical  San  Jose  scale,  and  there  is  no  basis  what- 
ever for  tl  e separation  of  these  specimens  as  a variety.  The  character 
on  which  the  variety  was  founded,  namely,  the  white  dot  surrounded 
by  a black  ring  marking  the  exuvia,  is  a feature  which  may  be  very 
commonly  found  in  the  San  Jose  scale  from  any  source. 

The  other  variety  established  by  Mr.  Cockerell  is  his  Aspidiotus 
perniciosus  var.  andromelas , first  described  in  California  Fruit  Grower, 
June  5,  1897,  on  a plant  labeled  “ Phoetenia  glauca ,”  from  Japan,  also 
received  from  Mr.  Craw.  This  variety  is  also  based  on  the  character 
of  the  covering  scale,  and  is  described  as  wholly  black  without  an} 
light  dot  and  ring,  a condition  which  is  easily  produced  by  rubbing  or 
otherwise  accidentally  and  may  occur  anywhere. 

A third  synonym  of  the  San  Jose  scale  is  Masked  s species  Aspi- 
diotus fusca , described  in  the  New  Zealand  Transactions,  Volume 
XXVII,  page  43-,  1894,  figures  6-9,  Plate  I.  This  insect  was  described 
from  material  collected  in  Australia  on  peach;  and  from  Maskell’s  own 
figures  and  account  of  it,  and  also  from  the  study  made  by  Leonardi 
in  Italy,  and  from  the  later  note  on  the  subject  by  Masked  himself  in 
the  Canadian  Entomologist,  it  is  evident  that  this  species  was  based 
on  material  representing  the  last  stage  of  the  female  of  perniciosus , 
but  before  the  secretionary  supplement  had  been  much  if  any  devel- 
oped, so  that  the  second  exuvium  was  still  larger  than  the  newly 
molted  insect.  This  point  can  not,  of  course,  be  fully  determined 
without  an  examination  of  type  material,  but  there  is  very  little  doubt 
in  the  writer’s  mind  of  the  correctness  of  this  reference. 

A fourth  variety  is  Aspidiotus  perniciosus  var.  eucalypti  Fuller. 
A study  of  material  received  from  Fuller  of  this  variety  indicates  that 
it  should  not  be  referred  to  the  San  Jose  scale  at  ad,  but  is  a good 
distinct  species  belonging  to  the  genus  Aonidiella,  and  the  name 
becomes  Aonidiella  eucalypti  Fuller. 

No  valid  varieties  or  subspecies  of  the  San  Jose  scale  have  therefore 
been  found,  and  ad  of  the  points  of  infestation  now  known  can  be 
traced  directly  to  the  Chinese  origin  of  the  scale. 


56 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


MEANS  OF  DISTRIBUTION. 

From  an  economic  standpoint  the  important  considerations  in  th< 
means  of  spread  of  this  insect  are  those  which  affect  its  wide  distribu 
tion  from  one  part  of  the  country  to  another.  The  transportation  bi 
nursery  stock  or  scions  or  budding  and  grafting  material,  as  indicate( 
in  the  foregoing  account  of  this  insect,  is  unquestionably  the  usua 
and  principal  means  of  carrying  the. insect  to  a distance.  The  impor 
tance  of  this  means  of  distributing  various  insects  has  only  been  fulh 
realized  in  this  country  in  the  last  few  years,  but  the  present  instanct 
and  some  other  notable  ones  of  like  nature  have  emphasized  the  grea^ 
danger  incurred  not  only  in  the  indiscriminate  introduction  of  plank 
from  foreign  sources,  but  also  in  the  carriage  of  plants  from  one  pari 
of  the  country  to  another  without  competent  inspection. 

The  San  Jose  scale  is  also  frequently  carried  about  on  fruit,  par- 
ticularly of  the  apple  and  pear.  The  young  scale  insect  goes  out  or 
the  fruit,  and  in  the  case  of  badly  infested  trees  there  is  usually  a good 
deal  of  scale  on  the  fruit  particularly,  massed  at  the  blossom  and  stem 
ends.  The  scale  may  go  on  breeding  on  such  fruit  and  the  young  maj 
be  found  crawling  about  on  the  fruit  and  in  the  boxes.  Such  fruit  h 
commonly  shipped  to  remote  points,  and  infested  fruit  may  be  found 
quite  commonly  in  the  markets  of  this  country;  and  when  attention 
was  drawn  to  the  San  Jose  scale  by  its  first  developing  in  the  East,! 
infested  fruit  from  California,  could  be  found  in  almost  any  of  the 
fruit  markets  of  the  principal  eastern  cities. 

The  shipping  of  infested  fruit  from  California  had  been  going  onl 
for  a great  many  years,  and  in  spite  of  its  wide  dissemination  in  this 
country,  and  to  some  extent  abroad,  there  is  not,  so  far  as  the  writer! 
knows,  a single  authenticated  instance  of  the  scale  having  been  estab-i 
lished  from  such  material.  The  possibility  of  it,  however,  undoubt- 
edly exists,  but  the  danger  seems  to  be  inconsiderable.  The  fruit  is] 
eaten  in  such  places  and  the  parings  and  waste  material  are  usually  ] 
disposed  of  in  such  a way  that  it  would  be  very  exceptional  indeed  for!] 
such  fruit,  or  the  young  scale  that  might  hatch  on  them,  to  get  access! 
to  trees  on  which  the  scale  could  make  lodgment.  It  would  practi- 
cal.}7 be  necessary  for  the  parings  to  be  tied  to  a tree,  or  the  fruit  to] 
be  placed  in  the  crotches  of  the  tree,  to  secure  infestation,  and  it  is] 
the  belief  of  the  writer  that  infestation  from  this  source  can  be  prac-ji 
tically  ignored.  This  has  an  important  bearing  on  the  legislation  i 
against  American  fruits  enacted  by  various  foreign  countries,  and  cer-'J 
tainly  the  history  in  this  regard  in  the  United  States  is  well  worth | 
considering  where  such  fruit  was  shipped  about  for  years  prior  to  the ; 
San  Jose  scale  scare  without  restrictions.  The  wide  distribution, 
therefore,  of  the  San  Jose  scale  is  substantially  limited  to  its  carriage] 
on  nursery  stock  and  cuttings. 


MEANS  OF  DISTRIBUTION. 


57 


The  local  spread  of  the  insect  from  orchard  to  orchard  and  from 
tree  to  tree  must  also  be  brought  about  thru  the  agency  of  means 
other  than  those  under  the  control  of  the  insect  itself.  The  female  is 
wingless  and  after  once  becoming  fixt  can  not  move.  The  young  lice, 
as  before  stated,  are  active,  crawl  rapidly,  and  may  reach  other  trees, 
but  this  is  rare  unless  the  limbs  interlace,  since  we  have  shown  by 
breeding-cage  experiments  that  the  lame  normally  crawl  but  a few 
inches.  Such  spread,  however,  is  comparatively  insignificant  except 
in  the  case  of  nursery  stock,  which  is  grown  close  together.  It  is 
possible  that  strong  winds  may  carry  the  young  bodily  from  one  tree 
to  another,  or  they  may  be  floated  on  water  to  distant  points,  particu- 
larly in  irrigated  districts,  but  the  principal  method  of  the  spread  of 
these  young  lice  is  by  means  of  other  insects  and  by  birds.  The  active 
[young  lice  soon  crawl  upon  any  small  winged  insect,  particularly  if 

> the  latter  be  of  a dark  color,  and  ma}^  thus  be  carried  considerable 
^distances.  They  are  frequently  found  crawling  upon  ants,  which  are 
great  travelers.  It  is  extremely  probable  that  they  also  crawl  upon 
the  feet  of.  birds,  and  may  be  transported  by  these  carriers  for  many 
miles. 

Some  interesting  observations  have  been  made  by  Mr.  Schwarz  upon 
the  transporting  of  these  scale  larvae  by  other  insects.  A little  black 
ladybird,  Microweisea  ( Pentilia ) misella  Lee.,  which  was  very  active 
in  devouring  scale  larvae,  was  unfortunately  equally  efficient  in  trans- 
porting many  of  these  young  lice  to  other  parts  of  the  tree  or  to  other 
trees;  in  fact,  it  was  difficult  to  find  a single  beetle  which  did  not  carry 
Dn  its  back  at  least  one  larva  of  the  San  Jose  scale,  and  sometimes  three 
pr  four  were  found  upon  a single  wing  cover  of  a beetle.  The  small 
black  ant,  Monornorium  minutum  Mayr,  was  particularly  abundant 
upon  pears,  attracted  by  the  juices  emerging  from  cracks,  and  almost 
every  one  of  these  insects  carried  on  its  back  one  or  more  specimens 
3f  the  young  scale  insects.  Specimens  of  the  little  chrysomelid  beetle 
Twipqphorus  canellus  Fab.  were  also  found  upon  the  trees.  Both  red 
md  black  specimens  of  this  beetle  occurred,  and  the  interesting  obser- 
vation was  made  that  while  Aspidiotus  larvae  crawled  freely  on  the 
; flack  individuals,  no  specimens  were  to  be  found  upon  the  red  ones. 
The  same  peculiarity  was  found  to  hold  true  with  the  ants.  The  red 
1 mt,  Formica  schaufussi  Mayr,  was  abundant  upon  the  pears,  but  no 

> specimens  were  found  bearing  Aspidiotus  larvae,  while,  as  just  stated, 
he  little  black  Monornorium  was  always  found  carrying  them. 

1 As  illustrating  this  transportation  of  the  scale  by  birds  or  insects 
die  experience  at  Riverside,  Md.  (Bui.  3,  p.  25),  may  be  cited,  and 
1 Professor  Smith  reports  a similar  instance  in  New  Jersey,  in  letter  of 
January  13,  1896. 

In  spite  of  the  abundance  of  insects  which  may  transport  the  larvae 
1 die  progress  of  the  scale  from  infested  trees  to  noninfested  trees  is 


58 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


slow  where  trees  are  moderately  widely  separated,  and  usually  an 
entire  orchard  will  not  become  affected  from  a single  original  point 
for  several  years. 

Occasionally  the  young  scales  may  be  locally  transported  >)3T  men  or 
teams.  An  interesting  case  in  point  is  given  by  Professor  Rolfs.  He 
states  that  some  melons  growing  in  an  infested  orchard  were  given  by 
the  owner  to  a friend,  who  took  them  away  from  the  orchard  in  his 
wagon.  A year  later  the  scale  developed  on  a tree  under  which  the 
team  had  been  hitched  while  the  melons  were  unloaded.  As  this 
orchard  was  entirely  free  from  the  scale  originally,  it  seems  to  be  a 
reasonable  inference  that  the  young  had  crawled  upon  the  wagon, 
harness,  or  melons,  were  conveyed  a distance  of  3 miles,  and  sue 
ceeded  in  gaining  access  to  a tree  which  probably  touched  the  wagor 
or  team  during  the  interval  of  unloading. 

PARASITES  AND  OTHER  NATURAL  ENEMIES. 

The  following  paragraphs,  under  the  heading  “True  parasites,’ 
were  prepared  for  this  bulletin  by  Dr.  L.  O.  Howard. 

TRUE  PARASITES. 

Some  eight  species  of  true  parasites  have  been  reared  from  the  Sail 
Jose  scale  in  this  country.  Nearly  all  of  these  are  widespread,  occur j 
ring  on  the  Pacific  coast,  and  generally  also  in  the  East,  and  are  found 
also  in  other  parts  of  the  world.  None  of  them  are  specific  enemiel 
of  the  San  Jose  scale  in  the  sense  that  they  are  limited  to  this  specie! 
of  scale,  but  all  of  them  are  general  parasites  on  other  Armored  seal! 
insects.  They  are  as  follows: 

Aphelinus  fuscipennis  Howard. 

Aphelinus  mytilaspidis  Le  Baron. 

Aspidiotiphagus  citrinus  Howard. 

Anaphes  gracilis  Howard. 

Physcus  varicornis  Howard. 

Prospalta  aurantii  Howard. 

Ablerus  clisiocampw  Ash  mead. 

Rhopoideus  citrinus  Howard. 

Of  these  Aspidiotiphagus  citrinus , Prospalta  aurantii , Aphelimm 
fuscipennis , and  Aphelinus  mytilaspidis  are  of  very  wide  distribution 
Aspidiotiphagus  citrinus , for  example,  originally  described  from  Calm 
fornia  in  181)1,  is  now  found  in  many  other  portions  of  the  United 
States,  in  the  West  Indies,  Italy,  Austria,  Ceylon,  China,  Formosa* 
Japan,  Cape  Colony,  Queensland,  South  Australia,  and  Hawaii,  ant 
this  remarkable  distribution  is  practically  followed  by  the  other  three} 

The  most  important  of  these  parasites  is  the  little  Aphelinus  fusem 
pennis.  It  was  reared  in  large  numbers  by  Mr.  Coquillett,  in  Cali  bn 
nia,  many  years  ago,  where  it  was  found  to  breed  thruout  the  ycai* 


TRUE  PARASITES. 


59 


specimens  being-  reared  as  late  as  November  10.  It  was  subsequently 
reared  many  times  by  Mr.  Alexander  Craw,  Mr.  E.  M.  Ehrhorn,  and 
others,  in  California.  In  the  East  it  attacked  the  San  Jose  scale  at 
the  very  outset,  having  previously  existed  in  this  part  of  the  country 
as  a parasite  of  other  species  of  Diaspinse.  It  was  reared  in  this 
office  from  material  collected  at  Riverside,  Md.,  and  Charlottesville, 
Va.,  and  also  from  the  material  collected  in  the  first  orchards  found 
infested,  by  Prof.  J.  B.  Smith,  of  New  Jersey.  Professor  Forbes  has 
reared  it  in  Illinois  from  the  San  Jose  scale,  and  it  has  often  been 
reared  in  Washington.  That  this  insect  has  been  steadily  on  the 
increase  seems  likely,  but  it  is  also  probable  that  there  is  a certain 
periodicity  in  its  increase.  In  Bulletin  No.  57  of  the  Maryland  Agri- 
cultural Experiment  Station,  published  in  August,  1898,  Prof.  W.  G. 
Johnson  stated  that  he  did  not  think  it  possible  to  secure  any  imme- 
diate beneficial  results  from  this  parasite  in  the  State  of  Maryland. 
He  said  that  in  all  his  efforts  to  secure  them  in  his  breeding  cages  he 
had  been  obliged  to  inclose  hundreds  of  thousands  of  scales  to  obtain 
one  parasite.  Less  than  two  years  later,  however, a he  stated  that  in  a 
new  locality  for  the  San  Jose  scale,  near  Easton,  Talbot  County,  Md., 
he  found  the  parasites  in  enormous  numbers.  A quantity  of  small 
branches  incrusted  with  the  scale  were  brought  to  his  laboratory  and 
inclosed  in  breeding  tubes.  Much  to  his  surprise  these  tubes  were 
swarming  with  parasites  a few  days  later.  From  one  tube  1,114  spec- 
imens of  Aphelinus  fuscipennis  were  taken,  while  a second  tube  gave 
432,  a third  1,478,  and  a fourth  more  than  1,000.  The  other  scale 
insects  infested  by  this  parasite  are  Aspidiotus  rapax  Comst.,  Aspidio- 
tus euonymi  Targ.,  Lepidosaphes  gloverii  Pack.,  and  Lepidosaphes 
ulmi  L. 

Aphelinus  mytilaspidis  Le  Baron  is  another  important  parasite  which 
was  reported  in  earlier  publications  as  attacking  the  San  Jose  scale  in 
California,  where  it  was  reared  in  Santa  Clara  County  btT  Mr.  E.  M. 
Ehrhorn.  It  is  also  a common  and  widespread  species,  and  infests, 
aside  from  the  San  Jose  scale,  Lepidosaphes  ulmi , Chionaspis  pin  ifolise 
Fitch,  and  Diaspis  carueli  Targ.  In  the  East  it  is  the  commonest 
parasite  of  the  oyster-shell  scale  of  the  apple.  It  has  only  recently 
been  found  to  attack  the  San  Jose  scale,  and  it  is  an  encouraging  fea- 
ture that  this  and  other  eastern  species  have  at  last  found  a host  satis- 
factory to  themselves  in  Aspidiotus  perniciosus . It  was  last  year 
(1905)  reared  at  this  office  from  San  Jose  scale  collected  at  Washington, 
I).  C.,  by  Mr.  A.  A.  Girault,  and  at  Youngstown,  N.  Y.,  by  Mr.  A.  L. 
Quaintance. 

Aspidiotiphagus  citrimis  Howard  (fig.  7)  is  one  of  the  most  impor- 
tant parasites  of  armored  scales  in  California,  to  which  State  it  was 
evidently  imported  from  oriental  regions.  In  California  it  has  been 


aBull.  No.  26,  new  series,  Division  of  Entomology,  U.  S.  Dept,  of  Agr.,  pp.  73,  74. 


60 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


repeatedly  reared  from  the  San  Jose  scale,  but  it  is  also  known  to 
attack  Chrysomphalus  ficus  Ashm.  and  G.  aurantii  Mask,  variety 
citrinus  Coq.  It  lias  made  its  way  to  the  East  and  has  been  reared 
from  the  San  Jose  scale  received  from  Hampton,  Fla.,  where  it  was 
collected  by  Mr.  A.  L.  Quaintance.  This  species  seems  to  be  found 
only  in  the  warmer  countries,  and  has  not  been  found  north  of  Florida 
in  the  East  as  yet. 

Anaphes  gracilis  Howard,  which  was  reported  in  Bulletin  No.  3 as 
originally  reared  from  specimens  collected  at  Riverside,  Md.,  and 
later  from  twigs  received  from  Charlottesville,  Va.,  has  not  again 
been  reared  in  this  office  from  the  San  Jose  scale,  and  the  doubt 
exprest  in  our  original  note  may  be  valid,  namely,  that  this  species 
may  have  been  a parasite  of  some  other  scale  insect,  probably  the 
oyster-shell  scale,  present  on  the  twigs  at  the  same  time.  The  type 
of  the  species  was  reared  from  the  oyster-shell  scale  of  the  apple,  and 
it  is  quite  likely  to  be  an  egg  parasite  only. 


The  four  species  just  mentioned  were  recorded  in  Bulletin  No.  3.  ; 
During  the  summer  of  1905  three  other  species  have  been  reared  by 
Messrs.  Quaintance  and  Girault.  These  are  as  follows: 

Physcus  varicornis  Howard  was  reared  from  material  collected  by  i 
Mr.  Quaintance,  May  30,  1905,  at  Hampton,  Fla.  There  remains  a i 
little  doubt  as  to  the  parasitism  of  this  species  on  perniciosus , as  j 
according  to  the  note  there  may  possibly  have  been  other  hosts  present. 
The  known  hosts  of  this  species  are  Aspidiotus  ancylus  Putn.,  Chion-  j 
aspis  quercus  Comst. , and  Chionaspis  arnericana  Johnson. 

Prospalta  aurantii  Howard  (tig.  8)  was  reared  from  the  San  Jose  i 
scale  July  31,  1905,  from  material  collected  from  an  infested  pear  tree 
on  the  grounds  of  the  Department  of  Agriculture,  at  Washington,  j 
This  parasite  affects  no  less  than  nine  distinct  species  of  scale  insects, 
and  has  been  reared  from  material  collected  in  California,  Florida,  j 
District  of  Columbia,  New  York,  New  Mexico,  and  Illinois. 


TRUE  PARASITES. 


61 


Ablerus  clisiocampae  Ashm.  (fig.  9)  was  reared  in  the  summer  of 
‘05  Messrs.  Quaintance  and  Girault  from  the  San  Jose  scale 
jeurring  upon  pear  upon  the  Department  grounds,  at  Washington. 


Fig.  8. — Prospalta  aurantii,  greatly  enlarged  (from  Howard). 


i was  also  reared  from  Diaspis  pentagona  Targ.,  occurring  upon 
le  grounds  of  the  Department.  It  affects  also  Chionctspis  furfurus 
itch,  and  is  known  to  occur  in  North  Carolina,  in  Illinois,  and  in  the 
istrict  of  Columbia. 


Fig.  9. — Ablerus  clisiocampse,  female,  greatly  enlarged  (from  Howard). 


Bhopoideus  citrinus  How.  was  reared  in  1885  by  Mr.  Albert 
k)ebele  at  Truckee,  Nevada  County,  Cal.,  from  Aspidiotus pernicio- 
us on  pear,  and  was  described  by  the  writer  in  the  proceedings  of  the 
1.  S.  National  Museum,  No.  1142,  October  4,  1898.  This  record  was 


62 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


overlooked  in  earlier  publications  from  this  Bureau,  and  the  specie 
has  not  since  been  reared  from  any  scale  in  any  part  of  the  country 
The  Koebele  1885  specimens  are  unique  so  far  as  known. 

PREDACEOUS  INSECT  ENEMIES. 

NATIVE  AND  INTRODUCED  ENEMIES  OF  OTHER  SCALE-INSECTS. 

Practically  all  of  the  scale-feeding  Coccinellidae,  or  ladybirds,  ma 
feed  on  the  larvae  or  older  specimens  of  the  San  Jose  scale.  A doze 
or  more  different  species  of  ladybirds  have  been  recorded  in  this  cour 
try  as  attacking  this  scale  insect.  Our  most  important  native  scab 
feeding  ladybird  (Chilocorus  bivulnerus  Muls.),  commonly  known  £ 
the  twice-stabbed  ladybird,  and  represented  by  one  species  or  by 
number  of  closely  allied  forms  in  different  sections  of  the  country 
has  not  proven  very  efficient  against  the  San  Jose  scale,  at  least  in  til 
East,  altho  commonly  found  in  infested  orchards.  Its  presence  1 
eastern  orchards,  however,  may  often  be  accounted  for  by  its  beinl 
attracted  by  other  ^native  scale  insects  present  in  the  same  orchard! 
It  is  a slow  breeder,  having  in  the  North  at  least  but  one  brocl 
annually,  and  seems  to  give  very  little  promise  of  being  of  an}r  grei 
value  as  a means  of  controlling  the  San  Jose  scale  in  these  sections  <1 
the  United  States.  In  California  and  elsewhere  on  the  Pacific  coasl 
but  particularly  in  the  Pacific  coast  region,  the  twice-stabbed  ladybiil 
is  a much  more  active  and  important  means  in  keeping  the  San  Jol 
scale  in  check.  It  has  been  reported  as  multipl}Ting  enormously  Sr 
infested  orchards  in  California  and  almost  effecting  the  exterminatio 
of  this  scale.  Such  a report  was  sent  to  us  by  Mr.  N.  W.  Mother! 
relative  to  orchards  in  Tulare  County,  Cal.a 

A large  number  of  Coccinellidie  imported  by  Mr.  Koebele  into  Cal 
fornia  and  colonized  there  have  been  reported  as  attacking  the  Sa 
Jose  scale.  The  following  species  have  been  observed  to  have  deva 
oped  this  habit:  Rhizobius  debilis  Black,  Orcus  australasise  Boiscl 
Rhizobius  lophanthse,  Blaisdell,  Orcus  chalybeus  Boisd.,  and  Mia fl 
weiseab  ( Pentilia ) misella  Lee.  The  last  named  of  these  only  is  of  ail 
importance  as  a means  of  controlling  the  San  Jose  scale/  Anothr 

« See  Insect  Life,  Vol.  V,  p.  53. 

&See  Cockerell,  Can.  Entom.,  Vol.  XXXV,  No.  2,  p.  38,  February,  1903. 

cThe  efficiency  against  scale  insect  pests  of  citrus  trees  of  certain  of  Mr.  Koebell 
importations  of  foreign  ladybirds  into  California  led  the  State  Horticultural  Sociei 
of  New  Jersey  to  secure  in  1896  from  the  State  legislature  an  appropriation  of  $1,(| 
for  the  purpose  of  importing  into  the  State  of  New  Jersey  the  natural  enemies  a l 
parasites  from  other  States  and  countries.  Acting  under  this  appropriation,  11 
John  B.  Smith,  entomologist  of  the  experiment  station  of  New  Jersey,  visited  Cm 
fornia  and  sent  a large  quantity  of  several  species  of  Australian  ladybirds  to  vari<i 
places  in  New  Jersey,  and  some  to  Washington,  D.  C.  Subsequent  records  of  th<I 
importations  indicated  that  they  were  all  unsuccessful,  and  not  a sign  of  the  import! 
insects  could  be  found  in  1897.  (See  Report  of  Entomologist,  New  Jersey,  1897. ) a 


ENEMIES  OF  OTHER  SCALE-INSECTS. 


63 


and  very  interesting  species  of  Microweisea,  recentl}'  described,  also 
attacks  the  San  Jose  scale,  and  is  referred  to  below. 

Rliizobius  lophanthse  was  originally  described  from  specimens  found 
Ippeying  upon  the  San  Jose  scale  at  San  Diego,  Cal.,  but  belongs  to  a 
Hot  which  was  introduced  by  Mr.  Koebele  on  his  first  Australian  trip 
(1888-89)  and  subsequently  lost  sight  of,  and  was  described  by  Doctor 
Blaisdell  under  the  supposition  that  it  was  a new  California  species. 

Of  our  native  predaceous  insects  attacking  the  San  Jose  scale,  the 
most  useful  and  interesting  is  the  little  coccinellid  Microweisea  misella 
(fig.  10),  which  in  both  the  larva  and  beetle  state  feeds  upon  this 
scale.  It  has  a very  wide  range,  occurring  thruout  the  East  and  also 


Fig.  10. — Microweisea  ( Pentilia ) misella:  a,  beetle;  b,  larva;  c,  pupa,  d,  blossom  end  of  pear,  showing 
scales  with  larvae  of  Microweisea  feeding  on  them,  and  pupae  of  Microweisea  attached  within  the 
calyx.  All  greatly  enlarged  (from  Howard  and  Marlatt). 

in  California,  and  began  to  attack  the  scale  in  numbers  in  the  East  in 
the  first  infested  orchards  discovered.  This  beetle  was  figured  and 
its  habits  briefly  indicated  in  Bulletin  3.  The  parent  beetles  prefer 
the  full-grown  female  scales,  and  may  frequently  be  observed  stand- 
ing astride  the  scale,  almost  on  end,  pushing  their  heads  under  the 
margin  of  the  protecting  scale  to  get  at  the  soft,  yellow  insect 
beneath.  The  larvae  of  these  beetles  seem  to  feed  more  abundantly  on 
the  young  scales.  Their  mode  of  attacking  the  older  scales  was  not 
observed.  The  egg  of  this  particularly  useful  coccinellid  has  not  been 
found,  but  a favorite  place  for  pupation  was  discovered  within  the 
calyx  of  the  pears.  This  cavity  is  often  literally  filled  with  a mixture 
8449— No.  62—06 5 


64 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


of  young  and  old  scale-insects,  and  frequently  contains  full-grown  | 
Pentilia  larvae,  their  pupae,  and  freshly  issued  beetles.  (See  fig.  10.) 

This  beetle  was  originally  believed  to  be  essentially  an  eastern  species, 
and  the  fact  that  it  attacked  the  San  Jose  scale  so  efficiently  at  the  very 
outset  was  an  interesting  entomological  experience,  and  led  Doctor 
Howard  to  suggest  its  immediate  introduction  int  > California,  and  one 
colony  was  sent,  in  1894,  to  Professor  Woodworth,  at  Berkeley.  Our 
account  of  this  useful  beetle  having  come  to  the  attention  of  Mr.  J.  E. 
McIntyre,  of  Lespe,  Cal.,  he  urged  us  to  procure  for  him  some  living 
specimens.  Having  already  sent  material  to  Mr.  Woodworth,  we  were  ) 
not  immediately  able  to  get  a supply  of  the  insects  for  a sending,  but 
at  this  juncture  we  received  from  Mr.  G.  W.  Harney,  of  Marysville, 
Cal.,  some  beetles  for  determination,  which  proved  to  be  Microweisea\ 
misella.  He  reported  that  in  the  mountainous  regions  of  Yuba  County 
many  apple  trees  had  been  very  badly  infested  with  A.  perniciosus , and 
that  hundreds  of  these  little  ladybirds  were  found  preying  on  the  scale. 
The  occurrence  of  this  ladybird  in  California  as  thus  determined,  and 
the  fact  that  it  there  had  the  same  useful  habit,  was  a most  interesting 
discovery.  We  immediately  had  Mr.  McIntyre’s  request  transferred 
to  Mr.  Harney  for  attention.  It  is  more  than  likely  that  this  little 
beetle  is  already  widely  distributed  over  the  Pacific  slope,  and  it  may 
prove  to  have  a continental  distribution  instead  of  being  restricted  to 
the  East,  as  originally  supposed. 

Another  species  of  about  the  same  size  as  Microweisea  misella , but! 
dark  wine-red  in  color  and  representing  a distinct  species,  has  been 
under  observation  for  some  time  by  Mr.  Frederick  Maskew  in  south- 
ern California,  and  at  the  time  of  the  writer’s  visit  to  California  in  the 
autumn  of  1903  his  attention  was  called  to  this  scymnid,  and  some  ) 
material  was  collected  and  submitted  to  Mr.  E.  A.  Schwarz,  who  pro- 
nounced it  to  be  an  undescribed  species.  Mr.  Maskew  states  that  this  ! 
little  scymnid  is  always  associated  with  the  San  Jose  scale,  and  seems  J 
to  be  doing  pretty  good  work  against  it.  Mr.  Schwarz  has  published! 
a description  of  it  under  the  name  Pseudoweisea  suturolis.a 

A small  predaceous  beetle,  Collops  quadrimaculatus  Fab.,  was] 
observed  by  Mr.  Schwarz  at  Charlottesville,  Va.,  feeding  on  the  larvae! 
of  the  San  Jose  scale.  This  beetle  belongs  to  the  family  Malachiidye,!  I 
concerning  the  life  history  and  food  habits  of  which  very  little  is 
known.  Evidently  these  beetles  are  in  part  at  least  predaceous,  aql 
evidenced  by  this  observation  by  Mr.  Schwarz.  This  beetle  is,  how-1 
ever,  not  abundant  enough  apparently  to  have  any  practical  value  as 
a means  of  controlling  the  San  Jose  scale. 

«Proc.  Ent.  Soc.  Wash.,  Vol.  VI,  No.  2,  April,  1904,  pp.  118,  119  (issued  May  21 J 
1904).  The  name  Pseudoweisea  was  used  by  mistake  for  Microweisea. — En. 


THE  ASIATIC-LADYBIRD  ENEMY  OF  THE  SCALE. 


65 


THE  ASIATIC-LADYBIRD  ENEMY  OF  THE  SAN  JOSE  SCALE. 

Thruout  the  region  investigated  in  China  and  Japan  (see  pp.  11-15), 
wherever  the  San  Jose  scale  occurred,  apparently  the  chief  natural 
agency  in  keeping  it  in  check  was  a small  ladybird,  Chilocorus  similis 
Rossi  (figs.  11,  12,  and  PI.  VII),  which  feeds  upon  the  scale  vora- 
ciously. This  beetle  is  almost  identical  in  appearance  with  the  twice- 
stabbed  ladybird  of  this  country,  Chilocorus  bivulnerus , in  the  adult 
stage,  but  in  the  larval  stage  differs  from  it  distinctlv  in  coloration. 


Fig.  11.— Asiatic  ladybird  (Chilocorus  similis),  oviposition  and  early  larval  stages:  a,  beetle  in  act  of 
thrusting  egg  beneath  scale;  b,  scale  slightly  raised,  showing  edge  of  egg  beneath;  c,  scale  lifted 
from  bark,  showing  manner  of  attachment  of  egg  to  the  inner  surface;  d,  view  of  egg  in  the  scale; 
e,  egg  magnified  to  show  sculpturing;  /,  three  eggs  placed  under  flap  of  bark;  g,  same,  natural  size; 
h,  i,  dorsal  and  lateral  views  of  newly  hatched  larva;  j,  larva,  first  stage,  feeding  on  mature  and 
young  scales.  All  enlarged  except  g (author’s  illustration). 

The  Asiatic  species  has  a skin  of  a reddish  or  flesh  tint,  with  black 
spines,  while  the  general  color  of  the  larva  of  the  native  species  is  a 
dull  gray,  which,  with  black  spines  common  to  both,  gives  the  latter  a 
very  much  darker  appearance.  There  are  also  certain  minute  struc- 
tural characters  which  can  be  made  out  only  with  the  use  of  the 
microscope.  There  is,  furthermore,  a very  distinct  difference  in  the 
habits  of  the  two  species,  the  Asiatic  ladybird  going  through  an  indefi- 
nite number  of  generations — four  or  five  annually,  depending  upon 
the  climate  and  latitude — and  the  American  species  having  much  fewer 


66 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


and  often  but  a single  generation  annually.  The  slowness  of  breeding 
of  the  American  species  is  a very  great  bar  to  its  usefulness  in  the 
latitude  which  includes  the  principal  deciduous-fruit  interests  of  the 
United  States. 

These  facts  were  thoroly  demonstrated  from  the  breeding  records 
of  the  material  sent  from  China  and  Japan.  Several  sendings  were 
made  by  the  writer,  but  unfortunately  most  of  the  specimens  died  in 
transit  or  during  the  first  winter.  Two  individuals,  however,  sur- 
vived, and  during  the  first  summer,  that  of  1902,  from  these  two  some 
5,000  or  more  beetles  were  secured.  The  breeding  was  first  carried: 


Fig.  12. — Asiatic  ladybird  ( Chilocorus  similis),  later  larval  stages,  pupa,  and  adult  insect:  a,  secondl 
larval  stage;  b,  cast  skin  of  same;  c,  full-grown  larva;  d,  method  of  pupation,  the  pupa  beingl 
retained  in  split  larval  skin;  e,  newly  emerged  adult' not  yet  colored;  /,  fully  colored  and  perfecll 
adult.  All  enlarged  to  the  same  scale  (author’s  illustration). 

on  in  cages  (PI.  VIII),  but  afterwards  the  beetles  were  liberated  in  the] 
small  experimental  orchard  attached  to  the  insectary  of  the  Bureau. 

A good  many  colonies  were  sent  out  to  different  States,  both  northl 
and  south,  in  the  summer  of  1902,  many  more  in  the  summer  of  1903| 
and  a few  additional  colonies  in  1904.  Many  of  these  colonies  were! 
liberated  under  rather  unfavorable  conditions,  or,  in  other  words! 
where  there  were  very  few  infested  trees,  and  the  beetles  probably 
became  scattered  and  lost.  The  best  success  came  with  certain  colo-1 
nies  sent  to  Georgia,  and  especially  the  notable  case  of  the  colony  all 
Marshall vi lie.  This  last  was  in  an  orchard  containing  some  17,00(1 


Bui.  62,  Bureau  of  Entomology,  U.  S.  Dept,  of  Agriculture. 


Plate  VII. 


Pupating  Larv/e  of  Chilocorus  similis  on  the  Terminals  of  Twigs  in 
Department  Orchard.  ' Author’s  Illustration.) 


LIBRARY 

UNIVERSITY  OF  ILLINOIS 
UR6ANA 


Bui.  62,  Bureau  of  Entomology,  U.  S.  Dept,  of  Agriculture. 


Plate  VIII 


Cages  Used  in  Breeding  Asiatic  Ladybird  (Chilocorus  similis ). 
'Author’s  Illustration.- 


LIBRARY 

UNIVERSITY  OE  ILLINOIS 
URBANA 


THE  ASIATIC-LADYBIRD  ENEMY  OF  THE  SCALE. 


67 


peach  trees,  covering  about  75  acres,  and  adjoined  a very  much  larger 
orchard  belonging  to  the  same  owner,  containing  250,000  trees.  The 
ladybirds  were  liberated  in  August,  1902,  in  the  smaller  orchard.  An 
examination  of  this  orchard  in  duly,  1903,  indicated  that  the  beetles 
were  rapidly  spreading,  and  that  they  would  soon  cover  the  smaller 
orchard.  An  estimate  at  this  time  of  the  number  of  ladybirds  in  all 
stages  placed  the  total  at  somewhere  between  25,000  and  40,000,  and 
from  observations  breeding  evident^  continued  at  this  point  up  to 
January.  There  was  therefore  in  this  latitude  at  least  a very  flatter- 
ing outlook  for  good  results  from  the  imported  beetle. 

None  of  the  colonies  sent  to  northern  States,  that  is,  north  of  the 
District  of  Columbia,  became  established  nor  gave  any  useful  results, 
and  subsequent  experience,  and  particularly  the  elaborate  tests  con- 
ducted by  Dr.  J.  B.  Smith,  in  New  Jersey,  would  indicate  that  there 
is  very  little  likelihood  of  usefulness  from  this  beetle  for  northern 
fruit  regions.  That  it  may  be  established  in  the  South  was  fully 
demonstrated  by  the  experience  noted  in  Georgia  and  by  the  experience 
in  the  orchard  attached  to  the  insectary  of  this  Bureau,  and  in  some 
other  similar  experiments  where  the  results  were  perhaps  less  marked. 

At  the  time  that  this  beetle  began  to  demonstrate  its  probable  con- 
siderable usefulness  in  Georgia  and  elsewhere  in  the  South,  the  prac- 
tical value  of  the  lime,  sulfur,  and  salt  wash  became  fully  established, 
and  all  commercial  orchards  were  regularly  subjected  to  spraying 
operations  with  this  mixture.  The  result  was  that  the  scale  food  of 
the  imported  beetle  was  almost  completely  destroyed,  and  this  was 
true  in  the  principal  orchards  where  it  was  doing  its  best  work.  As 
a consequence  all  of  the  beetles  starved  or  their  numbers  were  greatly 
reduced. 

The  local  stock  of  ladybirds  in  Washington  practically  disappeared 
with  the  gradual  extermination  of  the  scale  food,  and  by  the  action  of 
a native  parasite  which  began  to  attack  it  after  the  first  year.  This 
parasite  is  one  that  we  had  previously  reared  from  native  ladybirds 
and  had  supposed  it  to  be  a secondary  parasite;  but  the  fact  that  it  is 
a primary  parasite  became  fully  demonstrated,  and  it  attacked  the 
Washington  colony  with  such  vigor  as  to  practically  exterminate  it. 
Fortunately  this  same  parasite  does  not  seem  to  have  been  equally 
active  in  the  case  of  the  southern  colonies,  but  it  will  undoubtedly 
always  be  a bar  to  great  usefulness  from  this  and  allied  ladybirds. ° 

A very  serious  difficulty  in  the  introduction  and  establishment  of  a 
predaceous  insect  like  this  Asiatic  ladybird  beetle,  which  has  rather 
limited  powers  of  flight  and  is  not  carried  about  on  nursery  stock  as 
are  true  parasites,  is  the  very  scattering  nature  of  infestation  in  this 
country.  In  spite  of  the  fact  that  the  San  Jose  scale  has  become  so 

aSee  Proc.  Ent.  Soc.  Washington,  Vol.  V,  No.  2,  pp.  138,  139,  1903. 


68 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


widely  distributed  and  is  doing  so  much  damage  to  orchards,  it  is  still 
far  from  being  universally  present,  and  occurs  after  all  in  a very  scat- 
tering way  in  orchards  here  and  there,  with  often  20  or  30  miles 
between  places  of  infestation.  In  Japan  and  China,  where  the  Chilo- 
corus  occurs  rather  generally,  it  hnds  food  for  itself  in  every  country 
and  city  dooryard,  either  the  San  Jose  scale,  or,  in  Japan  particular^, 
the  white  peach  scale  (Diatpis  pentagona ),  on  which  it  also  feeds. 
The  stock  of  ladybirds,  therefore,  is  alwa}Ts  kept  up  in  greater  or  less 
numbers,  ready  to  take  hold  of  any  unusual  scale  increase.  In  this 
country,  if  the  local  food  supply  is  stopt  by  spraying  operations  or 
exhaustion,  the  ladybird  necessarily  dies,  and  very  rarely  will  go  far 
enough  to  find  another  infested  orchard  and  a new  food  supply.  Ulti- 
mately, when  the  San  Jose  scale  occurs  everywhere,  predaceous  lady- 
birds like  the  Asiatic  species  will  undoubtedly  become  much  more 
useful  than  they  are  under  present  conditions. 

Neither  the  Asiatic  ladybird  nor  any  other  predaceous  insect — and 
this  is  true  also  of  the  chalcidid  parasites,  tho  perhaps  in  a less  degree — 
can  ever  be  expected  to  so  thoroly  exterminate  the  San  Jose  scale  as 
to  give  sufficient  protection  for  commercial  orchard  purposes,  where 
absolutely  clean  or  unspotted  fruit  is  an  essential.  Predaceous  and 
parasitic  insects  can  only  survive  in  connection  with  their  host  species, 
and  therefore  ultimately  there  must  be  a natural  balance  which  will 
fluctuate  from  year  to  year  or  period  to  period,  in  which  alternately 
the  parasite  and  the  host  insect  get  the  upper  hand,  but  both  neces- 
sarily being  continuously  present.  Where  substantially  clean  fruit 
must  fie  had,  as  for  shipping  and  export  purposes,  spraying  or  some 
other  direct  means  of  control  must  be  practised;  and  now  that  an 
inexpensive  tree  wash  for  the  San  Jose  scale  has  been  discovered,  it 
is  very  much  to  the  advantage  of  everyone  to  spray  regularly,  rather 
than  trust  to  control  by  natural  enemies. 

The  importation  of  the  Asiatic  ladybird  and  the  action  of  other  pre- 
daceous enemies  and  of  parasites  can  not,  however,  work  anything  but 
good.  These  feed  upon  or  parasitize  and  destroy  scale  insects  and 
will  ultimately  greatly  reduce  the  virulence  of  the  attacks  of  the  San 
Jose  species.  The  larva  of  the  Asiatic  ladybird  was  observed  to  eat 
the  young  of  the  San  Jose  scale  at  the  rate  of  five  or  six  insects  to  the 
minute,  and  even  on  an  average  of  but  one  a minute  a total  of  1,440 
scale  insects  per  day  would  be  destro}red.  The  appetite  of  these  larvae 
seems  to  be  never  satisfied,  and  they  are  eating  practically  all  of  the 
time.  The  adults  also  feed  activety  on  the  scale.  In  addition  to  their 
greater  or  less  efficiency  in  generally  checking  the  rapid  multiplication 
of  the  San  Jose  scale,  they  and  other  natural  enemies  will  ultimateljT 
be  of  special  service  in  the  control  of  the  scale  in  private  grounds  and 
in  small  orchards  and  gardens  the  owners  of  which  would  not,  under 
ordinary  circumstances,  practise  regular  spraying  operations. 


FUNGOUS  AND  OTHER  DISEASES. 


69 

It  is  evident,  from  the  records  of  true  parasites  given  at  the  outset, 
that  native  parasites  are  beginning  more  and  more  to  attack  the  San 
Jose  scale.  The  native  predaceous  beetles  will  follow  suit,  and  un- 
doubtedly as  years  go  on  the  seriousness  of  San  Jose  scale  infestation 
will  diminish,  as,  in  fact,  it  has  already  done  in  California  and  perhaps 
noticeably  also  already  in  some  sections  in  the  East. 

FUNGOUS  AND  OTHER  DISEASES  OF  THE  SAN  JOSE  SCALE. 

Scale  insects  are  more  or  less  subject  to  control  bv  fungous  and 
other  diseases,  and  the  San  Jose  species  is  no  exception  to  this  rule. 
Control  by  these  agencies  is  particularly  efficient  in  the  moist  Tropics, 
so  much  so  that  most  scale  insects  are  practically  wanting  in  such 
regions.  The  armored  scales,  such  as  the  San  Jose  scale,  are  rarely  to 
be  met  with  in  tropical  regions  in  any  numbers,  and  where  found  are 
diseased  in  a large  percentage  of  cases.  The  mealy  bugs,  however, 
are  comparatively  immune.  The  efficiency  of  these  diseases  as  a means 
of  control  lessens  as  one  leaves  the  Tropics,  but  in  the  subtropical 
regions  of  the  United  States,  and  even  in  the  temperate  regions,  the  San 
Jose  scale  has  in  many  instances  been  very^  general^  exterminated  by 
disease.  Several  of  these  diseases  are  obscure  and  have  never  been 
scientifically  studied,  nor  have  they  developed  any  fruiting  stage  so 
that  they  could  be  studied  with  any  degree  of  accuracy. 

In  the  early  work  with  the  San  Jose  scale  in  California,  Mr.  Coquillett 
reports  the  death  of  the  San  Jose  scale  from  an  unaccountable  cause, 
supposedly  disease,  in  Pasadena  County,  Cal.,  on  pear  trees  which 
had  not  been  treated  with  any  kind  of  insecticide.  Specimens  of 
twigs  covered  with  dead  scales  were  submitted  to  the  Bureau  of 
Plant  Industry  for  examination.  No  specific  disease  germ  could  be 
discovered,  but  this  does  not  preclude  the  explanation  of  some  definite 
disease  as  the  cause  of  the  death  of  the  scales.  Similar  cases  have 
come  up  in  the  East  several  times,  the  first  perhaps  occurring  at  River- 
side, Md.,  in  the  early  history  of  the  scale,  where,  without  treatment, 
the  scale  died  in  a very  large  percentage  thruout  a considerable  orchard. 
A number  of  similar  cases  were  reported  by  Doctor  Howard  in  Bul- 
letin 12,  one  from  Tifton,  Ga.,  where  a careful  count  of  the  scales 
showed  that  on  one  twig  out  of  183  scales  4 were  living;  on  a second, 
out  of  723  scales  2 were  living,  and  on  a third,  out  of  579  scales  28 
were  living,  giving  34  living  scales  out  of  1,485,  a mortality  rate  of 
97.7  per  cent.  A similar  case  was  reported  also  from  Wadley,  Ga. , 
by  Professor  Starnes,  and  Professor  Alwood  has  noted  the  same  con- 
ditions at  Vienna,  Va.  Doctor  Howard  also  records  the  fungus- 
infested  scale  reported  by  Doctor  Fletcher  at  Fruitland,  Ontario,  altho 
here  the  fungus  or  disease  is  probably  a different  one. 

A more  promising  and  important  disease  of  the  San  Jose  scale  is 
the  cosmopolitan  scale-insect  parasitic  fungus  Sphaerostilba  coccophila , 


70 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


which  Professor  Rolfs,  of  the  Florida  experiment  station,  identified 
and  discust  at  length  in  Bulletin  41  of  that  station,  published  in 
1897.  This  disease  is  common  to  other  species  of  scale  insects,  is  ' 
widely  distributed  in  Florida  and  elsewhere  in  the  Southern  States,  i 
and  was  found  to  attack  the  San  Jose  scale  in  Florida  very  efficiently.  1 

As  outlined  by  Professor  Rolfs,  a San  Jose  scale  attacked  b}^  this 
fungus  is  usually  transformed  into  a mass  of  my celia  before  there  is  j 
any  external  appearance  of  change.  When  the  body  of  the  insect  has 
been  consumed  a br  ight,  orange-colored  protuberance  forms  at  the  I 
base  of  the  scale,  or  at  times  it  breaks  thru  the  protecting  cover  of  the 
insect.  This  orange-colored  protuberance  is  the  most  conspicuous 
part  of  the  fungus  and  the  only  portion  visible  to  the  unaided  eye. 
It  varies  in  size  from  an  eighth  to  a fortieth  of  an  inch.  Those  that 
average  about  one-sixteenth  of  an  inch  are  most  abundant  under  favor- 
able conditions.  These  protuberances  are  the  spore-bearing  bodies, 
and  contain  spores  in  great  numbers.  These  orange-colored  spore- 
bearing  bodies  are  developed  and  mature  within  six  weeks  from  the 
time  of  infection,  and  countless  numbers  of  spores  are  liberated  from 
them  during  rains  and  are  washed  down  the  trees  and  sometimes  to 
the  ground.  Other  and  smaller  spore  bodies  are  eventually  produced 
from  the  germination  of  these,  and  are  carried  about  by  the  air  or 
other  means,  and  thus  extend  the  infection.  The  biology  of  this 
fungus  is  rather  technical  and  complicated,  and  need  not  be  gone  into 
in  detail. a 

Professor  Rolfs  demonstrated  experimentally  that  this  fungus  could 
be  transferred  from  tree  to  tree  artificially.  His  process  was  to  inocu- 
late acid  bread  with  pure  cultures  of  the  fungus,  and  three  weeks  later 
to  break  up  a piece  of  bread  about  an  inch  square  in  cold  water,  and 
apply  to  a scaly  tree  by  means  of  a sponge  or  cloth  or  by  spraying. 
The  applications  were  made  in  midsummer,,  and  the  observations  as  to 
results  late  in  February.  Out  of  eight  experiments  four  were  success- 
ful, three  unsuccessful,  and  one  doubtful,  the  tree  having  in  the  mean- 
time died.  A good  deal  of  interest  was  aroused  by  this  publication 
of  Professor  Rolfs’s,  and  experiments  with  this  fungus  were  made  in 
Georgia  and  by  entomologists  to  whom  cultures  were  distributed  in  j 
the  North  and  West.  The  results  from  these  experiments  in  the  more 
northern  regions  were  not,  as  a rule,  very  satisfactory,  and  the  fun- 
gus has  not  demonstrated  great  practical  merit  outside  of  Florida  and 
perhaps  southern  Georgia.  Undoubtedly,  however,  it  is  a very  valu-| 
able  aid  in  the  control  of  the  San  Jose  scale  thruout  the  Gulf  region,  !j 
where  high  temperatures  associated  with  sufficient  humidit}7  occur. 

The  most  careful  experimental  work  with  this  fungus  was  that  con-  S 
ducted  by  Prof.  4.  B.  Smith  in  New  Jersey.  While  nearly  all  the! 


«See  Bui.  No.  41,  Florida  Agric*.  Exp.  Sta.,  1897. 


FUNGOUS  AND  OTHER  DISEASES. 


71 


experiments  made  by  Doctor  Smith  were  barren  of  results,  one  yielded 
rather  notable  success.  This  was  in  the  orchard  of  Mr.  Horace 
Roberts,  at  Fellowship,  N.  J.  Twigs  from  Florida  bearing  San  Jose 
scales  infested  by  the  fungus  were  tied  to  branches  of  infested  trees 
about  the  middle  of  June.  Toward  the  end  of  September  Doctor 
Smith  found  the  fungus  upon  almost  all  of  the  trees  upon  which  twigs 
had  been  tied.  He  reports  that  it  had  spread  pretty  well  over  the 
trees,  and  in  some  cases  its  presence  was  obvious  from  the  surface  of 
the  ground  to  the  extremity  of  the  branches,  hundreds  of  patches  of 
the  orange  fruiting  processes  being  everywhere  noticeable.  In  no 
case,  however,  so  far  as  Doctor  Smith  observed,  had  the  disease  spread 
to  any  adjacent  trees,  unless  in  a less  visible  stage,  and  by  no  means 
all  of  the  scales  on  the  trees  containing  these  twigs  were  dead. 

Various  saprophytic  fungi  which  develop  in  diseased  or  dying  wood 
are  sometimes  so  closely  associated  with  the  scale*  or  in  fact  grow  on 
the  scale  as  well  as  on  the  wood,  that  the  inference  is  a very  natural 
one  that  the  scale  is  being  killed  by  these  fungi.  Examples  of  two 
such  fungi  have  recentH  been  sent  to  us  for  examination  and  were 
submitted  to  the  Laboratory  of  Plant  Pathology  of  this  Department 
for  investigation.  The  following  report  indicates  their  nature: 

We  find  two  species  of  fungi  present  upon  these  specimens.  The  most  conspicuous 
form  is  Microperci  cotofieastri  (Fr. ) Sacc.  The  fungus  forms  small,  black,  somewhat 
pulvinate  masses  on  the  surface  of  the  bark,  sometimes  covering  old  scales.  The 
plant  is  not  mature  and  shows  in  only  a few  instances  pycnospores.  It  is  not  an 
uncommon  fungus  upon  diseased  or  dying  branches  of  fruit  trees  and  other  closely 
related  rosaceous  plants.  Its  relation  to  the  scales  present  is  probably  always  acci- 
dental. The  fungus  probably  develops  more  readily  upon  the  twigs  which  have 
been  injured  or  partially  killed  by  the  scale. 

There  is  also  another  fungus  present  in  a considerable  quantity  on  some  of  the 
twigs.  It  consists  of  minute  black,  slender  stipitate  bodies  a few  millimeters  high. 
This  is  also  immature,  showing  only  conidia.  It  is  probably  Spinctrina  cerasi  B.  & C. 
In  the  absence  of  the  ascigerous  form  of  the  fungus  it  is  impossible  to  state  positively 
that  this  is  the  species.  As  in  the  case  of  the  other  fungus  mentioned,  it  probably 
bears  no  parasitic  relation  to  the  scales  present,  as  it  usually  occurs  on  dead  or  dying 
branches  of  fruit  trees. 

The  first  fungus  mentioned  (Micropera)  is  the  one  most  closely  associated  with  the 
scales. 

The  plan  of  using  contagious  insect  diseases  to  destroy  important 
pests,  such  as  the  San  Jose  scale,  is  a very  attractive  one,  and  in  the 
case  of  the  San  Jose  scale  well  worthy  of  more  careful  study  than  has 
so  far  been  given  it.  It  is  possible  that  some  of  the  obscure  forms  of  dis- 
ease which  have  already  appeared  in  northern  districts,  as  in  ManJand, 
Virginia,  and  in  the  State  of  Washington,  may  be  capable  of  artificial 
propagation  and  distribution,  and  yield  results  of  distinct  value  in  the 
control  of  the  scale.  All  of  these  fungous  and  other  diseases  will 
undoubtedly  become  more  efficient  with  the  more  wide  and  general 
distribution  of  the  scale. 


72 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


MEANS  OE  CONTROLLING  THE  SAN  JOSE  SCALE. 

INSECTICIDE  APPLICATIONS. 

Active  experimentation . with  different  remedies  for  the  San  Jose 
scale  was  instituted  by  this  Office  promptly  after  the  discover}'  of  the 
occurrence  of  this  pest  in  eastern  orchards  and  nurseries.  A full 
record  of  these  early  experiments  is  given  in  Bulletin  No.  3 (new 
series)  of  this  Bureau,  pages  56  to  71.  The  subject  of  these  experi- 
ments will  not  be  gone  into  in  detail.  They  covered  the  use  of  the 
lime-sulfur  washes  employed  against  the  San  Jose  scale  in  California, 
the  hydrocyanic-acid-gas  treatment  for  orchards  and  nursery  stock, 
lye  washes,  pure  kerosene,  kerosene-soap  emulsions,  resin  washes,  and 
soap  washes.  The  early  experience  with  the  lime,  sulfur,  and  salt 
wash  was  unfavorable,  largely  due  apparently  to  the  fact  that  the 
observations  on  the  trees  treated  were  not  continued  long  enough  to 
note  the  effect  of  the  late  summer  results.  Good  results  were 
obtained  with  the  kerosene  emulsions,  and  particularly  with  the  soap 
washes,  and  the  fish-oil-soap  wash  became  one  of  the  standard  means 
of  controlling  the  scale  and  is  still  among  the  best  and  safest  washes 
to  be  used,  altho  rather  more  expensive  than  necessary,  except  where 
only  a few  trees  are  to  be  treated. 

The  subject  of  remedies  was  promptly  taken  up  by  different  experi- 
ment station  entomologists  in  the  East,  and  a vast  body  of  experimen- 
tal data  is  now  on  record  in  various  station  publications.  The  study 
of  the  subject  of  remedies  has  also  been  continued  by  this  Bureau  and 
reported  in  different  bulletins.  The  lime,  sulfur,  and  salt  wash  at 
first  reported  on  adversely  by  us  was  afterwards  demonstrated  to  be 
of  real  value,  and  experimental  work  was  taken  up,  first  by  the  Illinois 
Experiment  Station,  under  Professor  Forbes,  and  subsequently  by  other 
stations,  and  it  has  now  come  to  be  the  generally  accepted  remedy  for 
the  San  Jose  scale.  \Yithout  going  at  all  in  detail  into  the  subject 
historically,  it  is  sufficient  for  the  purpose  of  this  bulletin  to  reproduce 
the  recommendations  for  the  control  of  the  San  Jose  scale  substantially 
as  given  in  the  fourth  revised  edition  of  our  Circular  42. 

In  addition  to  the  standard  remedies  mentioned  below  a great  many 
proprietary  substances  have  appeared,  and  some  of  these  have  some 
merit.  The  best  of  these  are  certain  merchantable  brands  of  lime- 
sulfur  compounds,  and  oils  which  have  been  treated  by  some  secret 
process  to  render  them  miscible  in  water.  The  predominating  con- 
stituent of  the  latter  is  mineral  oil,  and  the  resulting  mixture,  which 
is  not  apparently  an  emulsion,  is  undoubtedly  of  value  if  used  in  suf- 
ficient strength  to  get  the  required  amount  of  oil  on  the  trees.  There 
is  no  advantage  in  using  any  of  these  compounds  over  the  standard 
insecticides,  and  their  greater  cost  is  a distinct  objection,  together 


THE  LIME-SULFUR  WASH. 


73 


,vith  the  uncertainty  of  composition.  Nevertheless,  where  only  a few 
:rees  are  to  be  sprayed  and  the  owners  would  probably  not  go  to  the 
rouble  of  preparing  a standard  emulsion  or  the  lime-sulfur  wash,  the 
use  of  miscible  oils  or  ready-made  lime-sulfur  washes  is  a good  deal 
better  than  nothing,  and  may  give  very  good  results.  Space  does  not 
permit  the  mention  and  discussion  of  a number  of  other  mixtures  which 
(have  not  proven  satisfactory  nor  the  equal  of  standard  means  of 
(control.  Some  of  these  have  been  experimented  with  somewhat 
extensively  by  different  experiment  station  entomologists. 

The  methods  of  control  which  have  been  especially  followed  in  the 
Eastern  States  are  (1)  the  lime-sulfur  wash,  (2)  the  soap  treatment, 
i(3)  treatment  with  pure  kerosene,  (4)  treatment  with  crude  petroleum, 

I (5)  treatment  with  mechanical  mixtures  of  either  of  the  last  two  oils 
with  water,  and  (6)  petroleum  emulsion  with  soap.  All  of  these 
methods  have  proved  themselves  to  be  successful  against  the  San  Jose 
scale  when  properly  carried  out.  As  compared  with  the  lime-sulfur 
: wash,  the  others  mentioned  are  more  expensive,  and  the  two  oils, 
unless  very  carefully  applied,  are  likely  to  injure  the  treated  plants 
and  are  now  seldom  used.  One’s  choice  of  method  must  therefore  be 
governed  by  availability,  special  needs,  and  experience.  In  the  main 
these  remedies,  including  the  lime-sulfur  wash,  are  winter  treatments 
and  ma}r  be  emplo3^ed  at  any  time  when  the  trees  are  in  dormant,  leaf- 
less condition.  The  weaker  oil-water  mixtures  and  the  emulsions  may, 
however,  be  used  in  the  growing  season.  The  treatments  enumerated 
are  all  for  trees  in  the  orchard.  Nursery  stock  badly  enough  infested 
to  require  such  treatment  is  best  destroyed.  For  the  general  disinfec- 
tion of  nursery  stock  the  hydrocyanic-acid-gas  treatment  is  the  standard 
and  only  satisfactory  means. 

THE  LIME-SULFUR  WASH. 

In  California,  where  this  scale  insect  first  occurred,  the  standard 
remedy  for  it  is  the  lime,  sulfur,  and  salt  wash,  a mixture  formerly 
used  as  a sheep  dip  in  Australia  and  employed  with  little  change  against 
the  San  Jose  scale,  and  by  a lucky  chance  proving  effective.  This 
wash  was  naturally  first  thought  of  on  the  discovery  of  the  San  Jose 
scale  in  eastern  orchards.  The  earlier  tests,  however,  conducted  by 
this  office  in  1894,  were  unfavorable,  and  the  experimentation  which 
followed  resulted  in  the  demonstration  by  ourselves  and  others  of  sev- 
eral distinct  and  valuable  methods  of  control  noted  below.  Later 
studies  of  the  action  of  this  wash  in  California  led  the  writer  in  1900 
to  give  it  a further  careful  trial  in  the  East,  Avith  most  successful 
results,  demonstrating  that  with  favoring  conditions,  i.  e.,  absence  of 
dashing  rains  for  a few  days  subsequent  to  the  application,  it  would 
give  just  as  good  results  in  the  Eastern  States  as  on  the  Pacific  coast. 


74 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


A year  later  (1901-2)  ver}r  elaborate  tests  conducted  by  Doctor  Forbes 
in  Illinois  showed  that  fairly  hard  rains  will  not  always  invalidate 
spraying  with  this  mixture.  A vast  amount  of  experience  of  the  most 
practical  kind  since  gained,  contributed  to  by  all  the  eastern  experi- 
ment stations  and  by  the  big  commercial  fruit  growers  of  the  Middle 
and  Eastern  States,  has  fully  demonstrated  the  practical  merit  of  this 
wash  and  its  superiority  to  others  in  point  of  safety  to  trees  and  in 
cheapness.  The  wash  is  furthermore  a valuable  fungicide  and  is  nota- 
bly useful  against  the  peach  leaf  curl,  sprayed  trees  being  practically 
immune  from  this  disease,  so  that  the  cost  of  treatment  is  often  more 
than  made  good  by  the  fungicidal  benefit  alone.  Its  disadvantages  are 
the  difficulty  of  preparation  and  the  heav}^  wear  which  it  entails  on 
apparatus — objections,  however,  which  do  not  offset  its  notable  advan- 
tages, particularly  for  commercial  orchard  work  or  where  the  number 
of  trees  to  be  treated  is  sufficient  to  warrant  the  trouble  of  its  prepara- 
tion . It  is,  in  fact,  the  standard  spray  now  used  in  commercial  orchards 
for  the  San  Jose  scale. 

In  the  matter  of  composition  of  the  wash  scarcely  any  two  experi- 
menters agree.  Salt  was  a part  of  the  original  composition  of  the  sheep 
dip  and  has  long  been  retained,  with  the  idea  that  it  added,  perhaps,  to 
the  caustic  qualities,  and  particularly  to  the  adhesive  nature  of  the 
wash.  For  the  latter  purpose  a very  small  amount  only,  1 or  2 pounds 
to  the  bushel  of  lime,  need  be  added,  following  the  custom  in  the 
preparation  of  whitewash  mixtures.  In  practical  experience,  however, 
the  salt  seems  to  have  been  of  very  little  benefit  and  is  therefore 
omitted  in  the  formula  now  given.  The  proportion  of  lime  and  sulfur 
is  a matter  of  some  indifference.  The  mixture  obtained  is  sulphide  of 
lime,  and  if  an  excess  of  lime  is  used  it  simply  remains  undissolved  in 
the  mixture  and  adds  to  the  whitewashing  character  of  the  application.  | 
Too  much  lime  is  distinctly  objectionable,  however,  because  of  the 
greater  difficulty  of  spraying  and  harder  wear  on  the  pump  and  nozzles. 
The  formula  here  given  is  substantially  the  one  which  has  been  hith- 
erto recommended  by  this  Bureau,  reduced  to  the  45  or  50  gallon  basis,  I 
or  the  capacity  of  the  ordinary  kerosene  barrel  commonly  used  in  its  I 
preparation  by  the  steam  method. 


Unslaked  lime pounds..  20 

Flowers  (or  flour)  of  sulfur do 15 

Water  to  make gallons..  45  to  50 


The  flour  of  sulfur,  although  requiring  somewhat  longer  cooking, 
seems  to  make  as  good  a wash  as  the  flowers  of  sulfur,  but  an  hour  of 
thoro  cooking  is  ample  for  either,  (food  qualit}7  stone  lime  should  be  j 
secured  and  slaked  in  a small  quantity  of  hot  water  in  the  cooking  | 
vessel,  say  one-third  the  full  dilution.  The  sulfur,  previously  mixt  j 
up  into  a stiff  paste,  should  be  added  at  once  to  the  slaking  lime.  The 


Bui.  62,  Bureau  of  Entomology,  U.  S.  Dept,  of  Agriculture. 


Plate  IX 


' : 


Steam  Plants  for  Cooking  Lime-Sulfur  Wash. 

(From  Quaintanee.) 


LIBRARY 

DIVERSITY  of  ILLINOIS 

urbana 


THE  SOAP  TREATMENT. 


75 

whole  mixture  should  be  boiled  for  at  least  one  hour,  either  in  an  iron 
kettle  over  a fire  out  of  doors  or  in  barrels  by  steam  (see  PI.  IX). 
Prolonged  boiling  increases  the  percentage  of  the  higher  sulphides, 
but  the  practical  end  is  obtained  with  a boiling  of  the  time  indicated. 
In  the  process  of  making,  the  color  changes  from  yellow  to  the  clear 
brown  of  sulphide  of  lime,  except  for  the  excess  of  lime  floating  in  it. 
After  an  hour’s  boiling  the  full  quantity  of  cold  water  can  be  added, 
and  the  mixture  should  then  be  promptly  applied  in  order  to  get  its 
full  strength  before  the  higher  sulphides  are  lost  by  cooling  and 
crystallizing  out.  In  transferring  to  the  spray  tank  it  should  be 
past  thru  an  iron  screen  or  strainer,  and  the  tank  itself  should  be  pro- 
vided with  an  effective  agitator. 

The  wash  is  a winter  application  and  can  not  be  applied  to  trees  in 
leaf.  It  may  be  applied  at  any  time  after  the  falling  of  foliage  in 
early  winter  and  prior  to  the  swelling  of  the  buds  in  spring.  It  wili 
probably  be  necessary  also  to  make  this  application  every  }~ear,  or  at 
le^st  as  often  as  the  San  Jose  scale  develops  in  anj'  numbers.  The 
wash  kills  the  San  Jose  scale  not,  only  by  direct  caustic  action,  but 
apparently  also  by  reason  of  the  coating  on  the  trees,  which  remains 
in  evidence  until  midsummer  or  later,  and  may  kill  or  prevent  the  set- 
tling of  any  }roung  scale  insects  which  may  come  from  parents  escaping 
the  winter  action. 

Two  applications  may  be  given  badly  infested  orchards — one  in  late 
fall,  the  other  in  late  spring.  Where  but  one  application  is  given,  the 
late  spring  just  before  the  buds  open  is  the  best  time. 

The  wear  on  pumps  and  nozzles  can  be  kept  to  a minimum  by  care- 
fully washing  the  apparatus  promptly  after  use.  The  Vermorel  nozzle 
is  the  best  one  for  the  wash,  and  additional  caps  may  be  secured  to 
replace  worn  ones.  The  use  of  an  air  or  other  gas  pressure  pump 
instead  of  the  ordinary  liquid  pump  will  save  the  wear  of  the  lime  on 
the  pump.  In  spraying  with  this  wash  clothing  is  ruined,  and  onty 
the  oldest  garments  should  be  worn.  Care  should  be  taken  also  to 
protect  the  eyes  to  avoid  unnecessary  inflammation. 

THE  SOAP  TREATMENT. 

Whale-oil  or  fish-oil  soap,  preferably  made  with  potash  lye,  is  dis- 
solved in  water  by  boiling  at  the  rate  of  2 pounds  of  soap  to  the  gallon 
of  water.  If  applied  hot  and  on  a comparatively  warm  day  in  winter, 
it  can  be  easily  put  on  trees  with  an  ordinary  spray  pump.  On  a very 
cold  day,  or  with  a cold  solution,  the  mixture  will  clog  the  pump,  and 
difficulty  will  be  experienced  in  getting  it  on  the  trees.  Trees  should 
be  thoroly  coated  with  this  soap  wash.  Pear  trees  and  apple  trees 
may  be  sprayed  at  an}^  time  during  the  winter.  Peach  trees  and  plum 
trees  are  best  sprayed  in  the  spring,  shortly  before  the  buds  swell. 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


76 

If  sprayed  in  midwinter  or  earlier,  the  soap  solution  seems  to  prevent 
the  development  of  the  fruit  buds,  and  a loss  of  fruit  for  one  year  I 
is  apt  to  be  experienced,  the  trees  leafing  out  and  growing,  however]* 
perhaps  more  vigorous^  on  this  account.  The  soap  treatment  is  per- 
fectly safe  for  all  kinds  of  trees  and  is  very  effective  against  the  scale! 
With  large  trees  or  badly  infested  trees,  preliminary  to  treatment  it 
is  desirable,  with  this  as  well  as  other  applications,  to  prune  then| 
back  very  rigorousty.  This  results  in  an  economy  of  spray  and  makes 
much  more  thoro  and  effective  work  possible.  The  soap  can  be  securecl 
in  large  quantities  at  from  3i  cents  to  I cents  a pound,  making  th  J 
mixture  cost,  as  applied  to  the  trees,  from  7 cents  to  8 cents  a gallon. 
The  success  of  the  soap  treatment  is  largely  influenced  by  the  quality! 
of  the  soap  used.  Many  brands  are  on  the  market,  mostly  made  with  I 
soda  lye.  A potash  soap  should  be  insisted  on,  and  one  that  does  not  I 
contain  more  than  30  per  cent  of  water.  The  soda  soap  washes  are 
apt  to  be  gelatinous  when  cold  and  difficult  or  impossible  to  spray! 
except  when  kept  at  a very  high  temperature. 

KEROSENE  TREATMENT. 

This  consists  in  spraying  the  trees  with  ordinary  illuminating  oil 
(coal  oil  or  kerosene).  The  application  is  made  at  any  time  during  the 
winter,  preferably  in  the  latter  part,  and  by  means  of  a spray  pump 
making  a fine  mist  spray.  The.application  should  be  made  with  the 
greatest  care,  merely  enough  spray  being  put  on  the  plant  to  moisten 
the  trunk  and  branches  without  causing  the  oil  to  flow  down  the  trunk 
and  collect  about  the  base.  With  the  use  of  this  substance  it  must  be 
constantly  borne  in  mind  that  careless  or  excessive  application  of  the 
oil  will  be  very  apt  to  kill  the  treated  plant.  The  application  should 
be  made  on  a bright,  dry  day,  so  that  the  oil  will  evaporate  as  quickhT 
as  possible.  On  a moist,  cloudy  day  the  evaporation  is  slow,  and 
injury  to  the  plant  is  more  apt  to  result.  If  the  kerosene  treatment 
be  adopted,  therefore,  it  must  be  with  a full  appreciation  of  the  fact 
that  the  death  of  the  tree  may  follow.  This  oil  has  been  used,  how- 
ever, a great  many  times  and  very  extensively  without  consequent 
injury  of  any  kind.  On  the  other  hand,  its  careless  use  has  frequently 
killed  valuable  trees.  Its  advantages  are  its  effectiveness,  its  avail- 
ability, and  its  cheapness,  kerosene  spreading  very  rapidly  and  much 
less  of  it  being  required  to  wet  the  tree  than  of  a soap  and  water  spray. 
Pure  kerosene  is  more  apt  to  be  injurious  to  peach  and  plum  than  to 
pear  and  apple  trees,  and  the  treatment  of  the  former,  as  with  the 
soap  wash,  should  be  deferred  until  spring,  just  before  the  buds  swell. 
With  young  trees  especially  it  is  well  to  mound  up  about  the  trunk  a 
few  inches  of  earth  to  catch  the  overflow  of  oil,  removing  the  oil- 
soaked  earth  immediately  after  treatment. 


THE  OIL- WATER  TREATMENT. 


77 


THE  CRUDE-PETROLEUM  TREATMENT. 

Crude  petroleum  is  used  in  exactly  the  same  way  as  is  the  common 
illuminating  oil  referred  to  above.  Its  advantage  over  kerosene  is 
that,  as  it  contains  a very  large  percentage  of  the  heavy  oils,  it  does 
not  penetrate  the  bark  so  readily,  and,  on  the  other  hand,  onty  the 
light  oils  evaporate,  leaving  a coating  of  the  heavy  oils  on  the  bark, 
which  remains  in  evidence  for  months  and  prevents  any  young  scale 
which  may  come  from  the  chance  individuals  that  were  not  reached 
by  the  spray  from  getting  a foothold.  Crude  petroleum  comes  in  a 
great  many  different  forms,  depending  upon  the  localit}T,  the  grade 
successfully  experimented  with  in  the  work  of  this  Bureau  showing 
43°  Baume.  Crude  oil  showing  a lower  Baume  than  43°  is  unsafe, 
and  more  than  45°  is  unnecessarily  high.  The  lower  specific  gravity 
indicated  (43°)  is  substantially  that  of  the  refined  product,  the  removal 
of  the  lighter  oils  in  refining  practically  offsetting  the  removal  of  the 
paraffin  and  vaseline.  The  same  cautions  and  warnings  apply  to  the 
crude  as  to  the  refined  oil. 

THE  OIL-WATER  TREATMENT. 

Various  pump  manufacturers  have  now  placed  on  the  market  spray- 
ing machines  which  mechanically  mix  kerosene  or  crude  petroleum 
with  water  in  the  act  of  spraying.  The  attempt  is  to  regulate  the 
proportion  of  kerosene  so  that  any  desired  percentage  of  oil  can  be 
thrown  out  with  the  water  and  be  broken  up  by  the  nozzle  into  a sort 
of  emulsion.  Some  of  these  machines,  when  everything  is  in  good 
working  order,  give  fairty  satisfactory  results,  but  absolute  relia- 
bility is  far  from  assured. 

The  best  outlook  for  good  apparatus  of  this  sort  seems  to  be  in  car- 
rying the  oil  and  water  in  separate  lines  of  hose  to  the  nozzle,  uniting 
them  in  the  latter,  and  in  maintaining  an  absolute  equality  of  pressure 
on  both  the  oil  and  the  water  tanks  by  employing  compressed  air  as 
the  motive  force,  kept  up  by  an  air  pump,  the  air  chamber  communi- 
cating with  both  of  the  liquid  receptacles.  Any  other  source  of  con- 
stant pressure,  as  carbonic  acid  gas  or  steam,  will  answer.  One  or 
more  manufacturers  are  now  working  on  apparatus  of  this  general 
description.  A 10-per-cent  strength  kerosene  can  be  used  for  a sum- 
mer spray  on  trees  where  the  San  Jose  scale  is  multiplying  rapidly  and 
where  it  is  not  desirable  to  let  it  go  unchecked  until  the  time  for  the 
winter  treatment.  The  winter  treatment  with  the  water-kerosene 
sprays  may  be  made  at  a strength  of  20  per  cent  of  the  oil.  Appli- 
cations of  the  oil-water  spray  should  be  attended  with  the  same  pre- 
cautions as  with  the  pure  oil,  and  there  is  even  somewhat  greater  risk, 
owing  to  the  natural  tendency  one  has  to  apply  the  dilute  mixture 
much  more  freely  than  the  pure  oil.  The  application  should  be  merely 


78 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


enough  to  wet  the  bark,  and  should  not,  to  any  extent,  at  least,  run 
down  the  trunk.  The  collection  of  water  and  oil  about  the  trunk  is  i 
just  as  dangerous  to  the  tree  as  is  that  of  the  pure  oil. 

In  the  use  of  the  oil  sprays  noted  above  one  who  has  not  had  expe-  I 
rience  with  them  is  advised  to  make  some  careful  preliminary  tests  to  j 
fully  master  the  process,  preferabty  waiting  two  or  three  weeks  to 
determine  the  results  before  entering  on  the  general  treatment  of  the  1 
orchard.  It  is  well,  also,  with  the  oil-water  mixtures,  to  test  the  pump  j 
from  time  to  time,  spraying  into  a glass  jar  or  bottle  to  determine  by 
actual  measurement  whether  the  correct  percentages  of  oil  and  water 
are  being  maintained. 

PETROLEUM-SOAP  EMULSIONS. 

The  kerosene-soap  emulsion,  following  chiefly  the  Riley-Hubbard 
formula,  has  been  one  of  the  standard  means  against  scale  insects  for 
twenty  years.  The  distillate  emulsion  generally  employed  in  Cali- 
fornia for  spraying  citrus  trees,  on  which  the  lime,  sulfur,  and  salt 
wash  can  not  be  used,  is  substantially  the  same  thing,  except  that  it 
is  made  with  the  California  distillate  or  petroleum  oil.  Crude  petro- 
leum of  an}^  kind,  as  well  as  the  refined  product,  may  also  be  used  in 
making  this  emulsion.  The  use  of  the  soap  emulsions  against  the  San 
Jose  scale  in  the  East  has  not  been  very  general,  on  account  of  the 
greater  facility  with  which  the  pure  oil  or  oil-water  mixtures  can  be 
applied.  The  difficulty  of  obtaining  uniform  results  with  the  latter 
has  led  to  a return  to  the  use  of  emulsions  to  some  extent,  and  there 
can  be  no  doubt  about  their  superior  merit  when  it  is  desired  to  dilute 
the  pure  oils.  Emulsions  may  be  applied  at  any  strength  with  abso- 
lute confidence  that  there  will  be  no  variation.  Where  the  emulsion 
can  be  prepared  wholesale  by  steam  power  its  employment  is  attended 
with  no  difficulties.  In  California  it  is  prepared  by  oil  companies  and 
sold  at  very  slightly  more  than  the  cost  of  the  oil  and  soap  ingredi- 
ents. It  is  made  after  the  following  formula: 


Petroleum . gallons . . 2 

Whale-oil  soap  (or  1 quart  soft  soap) pound. . I 

Water  ( soft ) gallon..  1 


The  soap,  first  finely  divided,  is  dissolved  in  the  water  by  boiling  and  ) 
immediately  added  boiling  hot,  away  from  the  fire,  to  the  oil.  The 
whole  mixture  is  then  agitated  violent^  while  hot  by  being  pumped  j 
back  upon  itself  with  a force  pump  and  direct-discharge  nozzle  throw-  ! 
ing  a strong  stream,  preferably  one-eighth  inch  in  diameter.  After 
from  three  to  five  minutes’  pumping  the  emulsion  should  be  perfect, 
and  the  mixture  will  have  increased  from  one-tbird  to  one-half  in 
bulk  and  assumed  the  consistency  of  cream.  Well  made,  the  emulsion 
will  keep  indefinitely  and  should  be  diluted  only  as  wanted  for  use, 


FUMIGATION  OF  NURSERY  STOCK. 


79 


Iii  limestone  regions,  or  where  the  water  is  very  hard,  some  of  the 
soap  will  combine  with  the  lime  or  magnesia  in  the  water,  and  more  or 
less  of  the  oil  will  be  freed,  especially  when  the  emulsion  is  diluted. 
Before  use  such  water  should  be  broken  with  lye,  or  rain  water 
should  be  employed. 

For  winter  sprays  dilute  the  emulsion  with  either  3,  4,  or  5 parts  of 
water,  giving  a percentage  of  oil  of  approximately  17,  13,  and  11  per 
cent.  The  strength  in  oil  of  this  application  on  trees  as  compared  with 
the  oil- water  sprays  is  the  equivalent  of  25,  20,  and  15  per  cent  oil, 
because  relatively  more  of  the  heavier  oil-soap  emulsion  is  held  by  the 
bark.  The  two  stronger  mixtures  may  be  used  on  the  apple  and  pear 
and  the  weaker  one  on  peach  and  plum. 

For  summer  applications  dilute  with  7,  10,  or  15  parts  of  water,  giv- 
ing approximately  8,  6,  and  4 per  cent  of  oil.  The  weaker  strengths 
may  be  used  on  trees  with  tender  foliage,  such  as  that  of  peach,  and  the 
greater  strength  for  strong  foliage  plants,  like  the  apple  and  pear. 

FUMIGATION  OF  NURSERY  STOCK. 

All  nursery  stock  which  is  under  the  least  suspicion  of  contamination 
with  the  San  Jose  scale  should  be  fumigated;  and  it  is  perhaps  worth 
while  to  fumigate  in  any  case  to  give  the  utmost  assurance  of  safety 
to  the  purchaser.  The  hydroc3ranic-acid-gas  fumigation  is  the  one  to 
use.  This  gas  is  generated  by  combining  potassium  cyanide,  sulfuric 
acid,  and  water.  The  proportions  of  the  chemicals  are  as  follows: 
Refined  potassium  cyanide  (98  per  cent),  1 ounce;  commercial  sulfuric 
acid,  1 ounce;  water,  3 fluid  ounces — to  every  100  cubic  feet  of  space 
in  the  fumigating  room  or  house.  The  latter  should  be  as  nearly  air- 
tight as  possible  and  provided  with  means  of  ventilation  above  and  at 
the  side,  operated  from  without,  so  that  at  the  end  of  the  treatment 
the  poisonous  gases  can  be  allowed  to  escape  without  the  necessity  of 
anyone  entering  the  chamber.  The  generator  of  the  gas  may  be  any 
glazed  earthenware  vessel  of  1 or  2 gallons  capacity,  and  should  be 
placed  on  the  floor  of  the  fumigating  room  and  the  water  and  acid 
necessary  to  generate  the  gas  added  to  it.  The  cyanide  should  be 
added  last,  preferably  in  lumps  the  size  of  a walnut.  Promptly  after 
adding  the  cyanide  the  room  should  be  vacated  and  the  door  made 
fast.  The  treatment  should  continue  forty  minutes.  It  must  be  borne 
in  mind  that  the  gas  is  extremely  poisonous  and  must  under  no  circum- 
stances be  inhaled.  The  gas  treatment  is  effective  against  the  scale  on 
growing  trees  in  the  orchard  also;  but  the  difficulty  and  expense  of 
the  treatment,  except  for  nursery  stock,  make  it  prohibitive  in  the  case 
of  deciduous  fruits. 


8449— No.  62-06- 


80 


THE  SAN  JOSE  OR  CHINESE  SCALE. 


LEGISLATION  AGAINST  THE  SAN  JOSE  SCALE. 

As  indicated  in  another  place,  no  insect  has  been  the  subject  of  so 
much  domestic  and  foreign  legislation  as  has  the  San  Jose  scale.  In 
this  country  nearly  all  the  States  have  past  laws  regulating  the  sale 
and  shipment  of  nursery  stock  and  providing  for  inspection  on  account 
of  this  scale  insect,  and  a great  many  foreign  countries  have  made 
regulations  regarding  the  importation  of  American  plants  and  fruits. 

The  domestic  legislation  on  insect  matters,  including  the  San  Jose 
scale,  was  compiled  by  Doctor  Howard  and  published  as  Bulletin  No. 
13  (new  series)  of  this  Office  in  1898,  and  the  foreign  legislation  up 
to  1900  is  summarized  by  Doctor  Howard  in  Circular  No.  41  of  this 
Office,  published  in  August,  1900.  There  has  been  a great  deal  of 
additional  legislation  by  different  States  subsequent  to  the  publication 
of  Bulletin  No.  13,  and  by  a resolution  of  the  Association  of  Economic 
Entomologists  and  the  American  Association  of  Horticultural  Inspect- 
ors this  Office  has  collected,  by  the  aid  of  special  committees  appointed 
by  the  two  associations  mentioned,  all  of  the  laws  in  their  present 
form,  and  these  have  very  recently  been  published  as  Bulletin  No.  61 
of  the  Bureau  of  Entomology.  There  have  been  also  some  charges 
in  foreign  legislation,  and  ultimately  a revision  of  Circular  41  will  be 
issued.  The  subject  is  much  too  large  and  bulky  to  be  considered  in 
this  bulletin. 


INDEX. 


Page. 

Ablerus  clisiocampx , scale  hosts 58,  61 

Acacia,  food  plant  of  San  Jose  scale 36 

Acer  platanoides,  food  plant  of  San  Jose  scale 38 

saccharinum,  food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

Actinidia  arguta , food  plant  of  San  Jose  scale 1 38 

poly  gam, a.  (See  Actinidia  arguta.) 

JEsculus  hippocastanum,  food  plant  of  San  Jose  scale 38 

Akebia  quinata,  food  plant  of  San  Jose  scale 36 

sp.,  food  plant  of  San  Jose  scale 36 

Alder.  (See  Alnus  sp. ) 

Almond.  (See  Prunus  amygdalus  and  P.  japonica.) 

Alnus  sp.,  food  plant  of  San  Jose  scale 38 

Althea,  shrubby.  (See  Hibiscus  syriacus .) 

Amelanchier  canadensis  and  spp.,  food  plants  of  San  Jose  scale 36 

Ampelopsis  quinquefolia,  food  plant  of  San  Jose  scale 38 

Anaphes  gracilis,  is  it  parasite  of  San  Jose  scale? 58,  60 

Ants,  spreading  San  Jose  scale 57 

Aonidiella  eucalypti,  not  variety  of  Aspidiotus  perniciosus 55 

Aphelinus  fuscipennis,  scale  hosts 58-59 

mytilaspidis,  scale  hosts 58,  59 

Apple.  (See  Pyrus  malus.) 

haw,  food  plant  of  San  Jose  scale 14 

Apricot.  (S ee  Prunus  armeniaca.) 

Arborvitse.  (See  Thuya  occidentalis. ) 

Aronia  nigra.  (See  Sorbus  melanocarpa.) 

Ash.  (See  Praxinus  sp.  and  F.  americana.) 

mountain.  (See  Sorbus  sp.,  S.  americana,  and  S.  aucuparia.) 

Aspidiotiphagus  citrinus,  scale  hosts 58,  59-60 

Aspidiotus  ancylus,  parasitized  by  Physcus  varicornis 60 

euonymi,  parasitized  by  Aphelinus  fuscipennis 59 

fusca  = Aspidiotus  perniciosus 55 

perniciosus.  ( See  also  Scale,  San  Jose. ) 

Aspidiotus  fusca  a synonym 55 

var.  albopunctatus  = Aspidiotus  perniciosus 55 

andromelas  = Aspidiotus  perniciosus 55 

eucalypti  = Aonidiella  eucalypti 55 

rapax,  parasitized  by  Aphelinus  fuscipennis , 59 

Basswood.  (See  Tilia  sp.  and  T.  americana. ) 

Beech,  purple-leaved.  (See  Fagus  sylvatica  var.  purpurea.) 

Betula  alba,  food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

Birch.  (See  Betula  sp.  and  B.  alba.) 


81 


82 


INDEX. 


Birds,  spreading  San  Jose  scale 

Blackberry,  common.  (See  Rubus  nigrobaccus.) 

Box.  ( See  Buxus.) 

Buxus,  food  plant  of  San  Jose  scale 

Castanea  americana , food  plant  of  San  Jose  scale 

Catalpa  bignonoides,  food  plant  of  San  Jose  scale 

common.  (See  Catalpa  bignonoides. ) 

sp.,  food  plant  of  San  Jose  scale 

Ceanothus  americanus,  food  plant  of  San  Jose  scale 

Celtis  occidental is,  food  plant  of  San  Jose  scale 

Cercidiphyllum  japonicum,  food  plant  of  San  Jose  scale 

Cherry.  (See  Prunus  avium,  P.  cerasus,  and  P.  pumila  var.  besseyi.) 

Chestnut.  ( See  Castanea. i americana. ) 

Chilocorus  bivulnerus,  comparison  with  Chilocorus  similis 

enemy  of  San  Jose  scale t : 

similis.  ( See  also  Ladybird,  Asiatic) . 

comparison  with  Chilocorus  bivulnerus 

Chinese  scale.  (See  Scale,  San  Jose,  and  Aspidiotus  perniciosus. ) 

Chionaspis  americana,  parasitized  by  Physcus  varicornis 

furfurus,  parasitized  by  Ablerus  clisiocampx 

pinifolise,  parasitized  by  Aphelinus  mytilaspidis 

quercus , parasitized  by  Physcus  varicornis . 

Chokeberry,  black.  ( See  Sorbus  melanocarpa. ) 

Chokecherry.  (See  Prunus  virginiana .) 

Chrysomphalus  aurantii  var.  citrinus,  parasitized  by  Aspidiotiphagus  citrinus 

ficus,  parasitized  by  Aspidiotiphagus  citrinus 

Citrus  aurantium.  ( See  also  Orange,  and  Citrus  fruits. ) 

food  plant  of  San  Jose  scale 

fruits  and  San  Jose  scale : . . 

trifoliata,  food  plant  of  San  Jose  scale 

Climate,  affecting  spread  of  San  Jose  scale 

Collops  quadrimaculatus,  enemy  of  San  Jose  scale 

Color  protection,  of  San  Jose  scale 

Cornus  alba  var.  sibirica,  food  plant  of  San  Jose  scale 

alternifolia,  food  plant  of  San  Jose  scale 

amomum,  food  plant  of  San  Jose  scale 

baileyi,  food  plant  of  San  Jose  scale 

candidissima , food  plant  of  San  Jose  scale 

circinata,  food  plant  of  San  Jose  scale. 

florida,  food  plant  of  San  Jose  scale 

sanguinea,  food  plant  of  San  Jose  scale 

stolonifera,  food  plant  of  San  Jose  scale 

Cotoneaster  sp.,  food  plant  of  San  Jose  scale 

vulgaris,  food  plant  of  San  Jose  scale 

• Crab  apple.  (See  Pyrus  sp. ) 

Cratsegus  coccinea,  food  plant  of  San  Jose  scale 

cordata,  food  plant  of  San  Jose  scale 

crus-galli,  food  plant  of  San  Jose  scale 

oxyacantha,  food  plant  of  San  Jose  scale 

sp.,  food  plant  of  San  Jose  scale 

Currant.  (See  Ribes  rubrum,  R.  nigrum,  and  R.  aureum.) 

Cydonia  japonica,  food  plant  of  San  Jose  scale 

vulgaris,  food  plant  of  San  Jose  scale 


Page. 

57 


38 

38 

38 

38 

38 

38 

38 


65-66 

62 

65-66 

60 

61 

59 

60 


60 

60 

38,  41 
42-43 
36,  41 
33-34 
64 
57 
36 

38 

39 
36 
39 
39 
39 
36 
38 

36,  42 

36 

37  I 
37  I 

37  if) 

42  § 
37 

37 

37 


INDEX. 


83 


Tage. 

Beutzia  sp.,  food  plant  of  San  Jose  scale 39 

Dewberry.*  (See  Rubus  villosus.) 

Diaspis  carueli,  parasitized  by  Aphelinus  mytilaspidis 59 

pentagona,  Asiatic  ladybird  an  enemy 68 

parasitized  by  Ablerus  clisiocampse 61 

Biospy r os  virginiana , food  plant  of  San  Jose  scale 39 

Diseases,  of  San  Jose  scale,  artificial  spread 70-71 

Distillate  emulsion.  (See  Petroleum-soap  emulsions.) 

Distribution  of  San  Jose  scale  affected  by  climate 33-34  - 

means 56-58 

Dogwood,  red  flowering.  (See  Cornus  florida.) 

Eleeagnus  longipes,  food  plant  of  San  Jose  scale 39 

sp.,  food  plant  of  San  Jose  scale 39 

Elder.  ( See  Sambucus  sp. ) 

Elm.  (See  TJlrnus  sp.,  IJ.  americana,  and  U.  campestris.) 

Entomosporium  maculatum,  resemblance  to  San  Jose  scale 35 

Eucalyptus  sp.,  food  plant  of  San  Jose  scale 39 

Euonymus  sp.,  food  plant  of  San  Jose  scale 39 

Fagus  sylvatica  var.  purpurea , food  plant  of  San  Jose  scale 37 

Ficus  carica , food  plant  of  San  Jose  scale , 39 

Fig.  (See  Ficus  carica.) 

Forsythia  sp.,  food  plant  of  San  Jose  scale 39 

Fraxinus  americana , food  plant  of  San  Jose  scale 39 

sp.,  food  plant  of  San  Jose  scale 39 

Formica  schaufussi,  not  carrying  San  Jose  scale 57 

Fumago  salicina,  on  San  Jose  scales 51 

Fumigation  of  nursery  stock  against  San  Jose  scale 79 

Fungi,  saprophytic,  accidental  occurrence  on  San  Jose  scale 71 

Fungicide,  lime-sulfur  wash 8 

Fungous  and  other  diseases  of  San  Jose  scale 69-71 

diseases  destructive  to  armored  scales  in  Tropics 34,  69 

Fungus.  (See  Entomosporium  maculatum,  Micropera  cotoneastri,  Sphserostilbe 
coccophila,  and  Spinctrina  cerasi. ) 

Fungus,  sooty.  (See  Fumago  salicina.) 

Gleditschia  triacanthos,  food  plant  of  San  Jose  scale 39 

Globe  flower.  (See  Kerria  japonica.) 

Gooseberry.  (See  Ribes  oxyacanthoides.) 

Grapes.  (See  Vitis  sp.) 

Hawthorn.  (See  Crataegus  sp.  and  C.  oxyacantha. ) 

Hibiscus  syriacus,  food  plant  of  San  Jose  scale 39 

Hicoria  pecan,  food  plant  of  San  Jose  scale 39 

Honeysuckle.  (See  Lonicera  sp. ) 

Hop  tree.  (See  Ptelea  trifoliata.) 

Horse-chestnut.  ( See  JEsculus  hippocastanum. ) 

Hydrocyanic-acid  gas.  (See  Fumigation.) 

Insect  legislation 80 

Insecticides  against  San  Jose  scale 72-79 

Insects  spreading  San  Jose  scale * 57 

Juglans  nigra,  food  plant  of  San  Jose  scale 39 

regia,  food  plant  of  San  Jose  scale 39 

sieboldiana,  food  plant  of  San  Jose  scale 37 

Juneberry.  (See  Amelanchier  canadensis. ) 

Kalmia  latifolia,  food  plant  of  San  Jose  scale 39 


84 


INDEX. 


Kerosene  emulsion.  ( See  Petroleum-soap  emulsions. ) Page. 

remedy  for  San  Jose  scale 76 

Kero-water.  (See  Oil- water. ) 

Kerria  japonica,  food  plant  of  San  Jose  scale 39 

Ladybird,  Asiatic.  (See  also  Chilocorus  similis.) 

enemy  of  Diaspis  pentagona 68 

San  Jose  scale 65-69 

twice-stabbed.  (See  Chilocorus  bivulnerus.) 

Ladybirds,  Australian,  unsuccessful  importation  into  New  Jersey 62 

Laurel,  mountain.  ( See  Kalrnia  latifolia. ) 

Legislation  against  San  Jose  scale 80 

Lemon.  ( See  Citrus  fruits. ) 

Lepidosaphes  gloverii,  parasitized  by  Aphelinus  fuscipennis 59 

ulmi.  (See  also  Scale,  oyster-shell.) 

parasitized  by  Aphelinus  mytilaspidis 1 59 

Ligustrum  ovalifolium,  food  plant  of  San  Jose  scale 39 

vulgar e,  food  plant  of  San  Jose  scale 37,  41 

Lilac.  (See  Syringa  vulgaris-and  S.  persica. ) 

Lime-sulfur  wash  detrimental  to  establishment  of  Asiatic  ladybird 67 

remedy  for  San  Jose  scale 73-75 

value  as  fungicide 8 


Linden.  (See  Tilia  sp.  and  T.  americana. ) 
Locust.  (See  Robinia  sp. ) 

honey.  (See  Gleditschia  triacanthos.) 


Lonicera sp.,  food  plant  of  San  Jose  scale 39 

Maple.  (See  Acer  sp.,  A.  ploianoides,  and  A.  saccharinum.) 

Micropera  cotoneastri,  accidental  occurrence  on  San  Jose  scale 71 

Microweisea  misella,  enemy  of  San  Jose  scale 62,  63-64 

spreading  San  Jose  scale 57 

[ Pseudoweisea ] suturalis,  enemy  of  San  Jose  scale 64 

Monomorium  minutum , spreading  San  Jose  scale 57 

Morus  sp.,  food  plant  of  San  Jose  scale 39 

Mountain  ash.  (See  Sorbus  sp.,  S.  americana,  and  S.  aucuparia.) 

Mulberry.  (See  Morus  sp.) 

Oil  water,  remedy  for  San  Jose  scale 77-78 

Orange.  (See  also  Citrus  fruits  and  Citrus  aurantium.) 

hybrid  of  trifoliate  with  sweet,  infestation  by  San  Jose  scale 42  i 

mandarin  or  tangerine  type,  infestation  by  San  Jose  scale 43 

trifoliate.  (S ee  Citrus  trifoliata.) 

Orcus  australasise,  enemy  of  San  Jose  scale 62  k| 

chalybeus,  enemy  of  San  Jose  scale 62  1 1 

Osage  orange.  (See  Toxylon  pomiferum.) 

Peach.  (See  Prunus  persica. ) 

Chinese  flowering,  food  plant  of  San  Jose  scale 14  r 

Pear.  (See  also  Pyrus  communis.) 

Kieffer.  (See  also  Pyrus  sinensis.) 

immune  to  San  Jose  scale 42 

Leconte,  immune  to  San  Jose  scale .421 

orchards,  in  Japan 11-12| 

sand,  including  Kieffer.  (See  Pyrus  sinensis,  and  Pear,  Kieffer.) 

Pecan  nut.  (See  1 Peoria  pecan.) 

Pentilia  misella — Microweisea  misella 571 

Pernicious  scale.  (See  Scale,  San  Jose,  and  Aspidiotus  perniciosus. ) 

Persimmon.  (See  Diospyros  virginiana. ) 


INDEX. 


85 


Petroleum,  crude,  remedy  for  San  Jose  scale 

soap  emulsions,  remedies  for  San  Jose  scale 

Phcetenia  glauca,  food  plant  of  Aspidiotus  perniciosus  var.  andromelas 

Photinia  villosa,  food  plant  of  San  Jose  scale 

Physcus  varicornis,  is  it  parasite  of  San  Jose  scale? 

scale  hosts 

Physocarpus  opulifolius,  food  plant  of  San  Jose  scale 

Picea  alba,  food  plant  of  San  Jose  scale 

Plum.  (See  Prunus  maritima , P.  domestica,  P.  triflora , P.  cerasifera  var.  atro- 
purpurea,  and  P.  hortulana. ) 

Poplar.  (See  Populus  sp.,  P.  deltoides,  and  P.  nigra  var.  italica.) 

Populus  deltoides,  food  plant  of  San  Jose  scale 

nigra  var.  italica,  food  plant  of  San  Jose  scale 

sp.,  food  plant  of  San  Jose  scale , 

Privet.  (See  lAgustrum  vulgare  and  L.  ovalifolium. ) 

Prospalta  aurantii,  parasite  of  San  Jose  scale 

Protective  resemblance,  in  San  Jose  scale 

Prunus  amygdalus,  food  plant  of  San  Jose  scale 

armeniaca,  food  plant  of  San  Jose  scale 

avium,  food  plant  of  San  Jose  scale 

cerasifera  var.  atropurpurea,  food  plant  of  San  Jose  scale 

cerasus,  food  plant  of  San  Jose  scale 

domestica,  food  plant  of  San  Jose  scale 

hortulana,  food  plant  of  San  Jose  scale . 

japonica,  food  plant  of  Jan  Jose  scale 

maritima,  food  plant  of  San  Jose  scale 

persica,  food  plant  of  San  Jose  scale 

pissardi.  (See  Prunus  cerasifera  var.  atropurpurea.) 

pumila,  food  plant  of  San  Jose  scale 

var  besseyi,  food  plant  of  San  Jose  scale 

serotina,  food  plant  of  San  Jose  scale 

triflora,  food  plant  of  San  Jose  scale 

virginiana,  food  plant  of  San  Jose  scale 

Pseudoweisea  suturalis=Microweisea  suturalis 

Ptelea  trifoliata,  food  plant  of  San  Jose  scale 

Pyrus  baccata,  food  plant  of  San  Jose  scale 

communis.  (See  also  Pear.) 

food  plant  of  San  Jose  scale : 

malus.  ' (See  also  Apple. ) 

food  plant  of  San  Jose  scale 

sinensis.  (See  also  Pear,  Kieffer. ) 

food  plant  of  San  Jose  scale 

sp.,  food  plant  of  San  Jose  scale 

Quince.  (See  Cydonia  vulgaris  and  C.  japonica.) 

Raspberry,  red.  (See  Rubus  strigosus.) 

Rhizobius  debilis,  enemy  of  San  Jose  scale . „ .... 

lophanthse , enemy  of  San  Jose  scale 

Rhodotypos  kerrioides,  food  plant  of  San  Jose  scale 

Rhopoideus  ciirinus,  parasite  of  San  Jose  scale 58 

Rhus  cotinus,  food  plant  of  San  Jose  scale 

sp.,  food  plant  of  San  Jose  scale 

Ribes  aureum,  food  plant  of  San  Jose  scale 

nigrum,  food  plant  of  San  Jose  scale  


Page. 

'll 
78-79 
55 
39 
58,  60 
60 
39 
39 


37 

37 

37 

58,  60 
57 
37 
37 
37 
37 

39, 41 
37 
37 
37 
37 
37 

37 

37 

37 

37 

37 

64 

37,  41 
37 


37 

37 


62 

62 

39 

61-62 

39 

39 

37 

37 


INDEX. 


86 

Page. 

Ribes  oxyacanthoides,  food  plant  of  San  Jose  scale 37 

rubrum,  food  plant  of  San  Jose  scale 37 

Robinia  sp.,  food  plant  of  San  Jose  scale 39 

Rosa  Carolina , food  plant  of  San  Jose  scale 37 

lucida,  food  plant  of  San  Jose  scale 37 

rugosa,  food  plant  of  San  Jose  scale 38, 42 

sp.,  food  plant  of  San  Jose  scale 37 

virginiana,  food  plant  of  San  Jose  scale.  38 

Hose,  Japanese.  (See  Kerria  japonica. ) 

Rubus  canadensis.  (See  Rubus  villosus. ) 

nigrobaccus  (R.  villosus),  food  plant  of  San  Jose  scale 39 

strigosus,  food  plant  of  San  Jose  scale ’ 39 

villosus  (R.  canadensis ),  food  plant  of  San  Jose  scale 39 

Salix  bdbylonica,  food  plant  of  San  Jose  scale 38 

humilis,  food  plant  of  San  Jose  scale 38 

incana,  food  plant  of  San  Jose  scale. . .• 38 

lucida,  food  plant  of  San  Jose  scale 38 

pentandra,  food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

vitellina,  food  plant  of  San  Jose  scale 38 

Sambucus  sp.,  food  plant  of  San  Jose  scale 39 

San  Jose  scale.  (See  Scale,  San  Jose.) 

Sassafras.  (See  Sassafras  officinale.) 

officinale,  food  plant  of  San  Jose  scale 39 

Scale,  Chinese.  (See  Scale,  San  Jose,  and  Aspidiotus  perniciosus.) 

insects,  various  methods  of  reproduction 43-44 

oyster-shell.  (See  also  Lepidosaphes  ulmi.) 

probably  parasitized  by  Anaphes  gracilis 60 

pernicious.  (See  Scale,  San  Jose,  and  Aspidiotus  perniciosus.) 

San  Jose.  (See  also  Aspidiotus  perniciosus.) 

activity  of  young  larva 43, 45, 51,  57 

adult  female,  description 54 

male,  description 53 

and  citrus  fruits 42-43 

climate  as  affecting  spread 33-34 

color  protection 57 

control 72-79 

damage,  nature ^ 34-36 

descriptions  of  scale  and  insect 51-54 

destructiveness 7 

distribution  and  present  condition,  by  States  and  Territo- 
ries   18-33 

by  faunal  zones 33-34 

means 56-58 

egg,  description 51-52 

explorations  in  eastern  Asia  to  determine  origin. . 11-15 

fecundity 48-51 

female,  third  stage,  description 53 

first  establishment  in  the  United  States 10 

food  plants 36-43 

fungous  and  other  diseases 34, 69-71 

generations 48-50 

habits  and  life  history 34-55 

hibernation 43,  50 


INDEX. 


87 


Page. 

Scale,  San  Jose,  history  in  California  and  the  West 15 

East 16-17 

immunity  of  Leconte  and  Kieffer  pears 42 

in  Alabama 20 

Arizona 20 

Arkansas 20 

Australia 10 

California 20-21 

Canada 33 

Chile 10 

China 13-15 

Colorado 21 

Connecticut 21 

Delaware 21 

District  of  Columbia ./■ 22 

Florida 22 

Georgia 22 

Hawaiian  Islands 10 

Idaho 22-23 

Illinois 23 

Indiana 23 

Iowa 23 

Japan 11-13 

Kansas 24 

Kentucky 24 

Louisiana 24 

Maine 24 

Maryland 25 

Massachusetts - 25 

Michigan 25-26 

Minnesota * 26 

Mississippi 26 

Missouri 26 

Montana 26 

Nebraska 26 

New  Hampshire 26-27 

New  Jersey 27 

Nevada 27 

New  Mexico 27 

New  York 27-28 

North  Carolina 28 

North  Dakota 28 

Ohio 28 

Oklahoma 29 

Oregon 29 

Pennsylvania 29-30 

Rhode  Island 30 

South  Carolina 30 

South  Dakota 30 

Tennessee 30-31 

Texas 31 

Utah 31 

Vermont 31 

Virginia 31-32 


88 


INDEX. 


Page. 

Scale,  San  Jose,  in  Washington - 32 

Wisconsin 32 

West  Virginia - 32-33 

W yoming. 32 

indirect  benefits . . 9 

insect  enemies,  status - 9, 58-69 

insecticides 72-79 

introduction  into  United  States,  supposed  manner 15 

issuance  of  adult  males 47 

larva,  second  stage,  description  52 

newly  hatched,  description 52 

legislation 80 

life  history 43-51 

on  Chinese  apples,  haw  apples,  and  pears 14 

origin 10-15 

parasites 58-62 

plants  commonly  or  badly  infested 36-38 

not  infested 40-41 

occasionally  or  rarely  infested 38-39 

predaceous  insect  enemies 62-69 

present  status  of  problem 8-10 

propupa  of  male,  description 52-53 

pupa  of  male,  description 53 

record  of  spread  in  United  States 15-34 

relationships 54-55 

remedies 72-79 

reproduction 43-45,  50-51 

resemblance  to  Entomosporium  maculatum 35 

scale  covering,  how  formed 45 

of  female,  description 51 

male,  description 51 

seasonal  history 43-50 

sources  of  infestation  in  East 17-18 

States  still  supposedly  uninfested 19-20 

systematic  position 54-55 

viviparous  habit 43-45 

white  peach.  (See  Diaspis pentagona.) 

Scales,  armored,  subject  to  fungous  diseases  in  Tropics 34,  69 

Shad-bush.  (See  Amelanchier  canadensis.) 

Smoke  bush.  (S ee  Rhus  cotinus.  ) 

Snowberry.  (See  Symphoricarpos  racemosus. ) 

Soap,  whale-oil  or  fish-oil,  remedy  for  San  Jose  scale 75-76 

Sorbaria  sorbifolia  ( Spiraea  sorbifolia),  food  plant  of  San  Jose  scale 39 

Sorbus  americana,  food  plant  of  San  Jose  scale 38 

aucuparia,  food  plant  of  San  Jose  scale 38 

melanocarpa , food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

Sphaerostilbe  coccophila,  fungous  enemy  of  San  Jose  scale 34,  69-71 

Spinctrina  cerasi,  accidental  occurrence  on  San  Jose  scale 71 

Spiraea  sorbifolia.  (See  Sorbaria  sorbifolia.) 

sp.,  food  plant  of  San  Jose  scale 39 

Spruce,  white.  (See  Picea  alba.) 

Sumac.  (See  llhus  sp. ) 

Symphoricarpos  racemosus , food  plant  of  San  Jose  scale 38 


INDEX. 


89 


Page. 

Syringci  persica,  food  plant  of  San  Jose  scale 38 

vulgaris , food  plant  of  San  Jose  scale 38 

Thorn,  silver.  (See  Elxagnus  long ipes.) 

Thuya  occidentals,  food  plant  of  San  Jose  scale 39 

Tilia  americana,  food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

Toxylon  pomiferum,  food  plant  of  San  Jose  scale 38 

Typophorus  canellus,  spreading  San  Jose  scale 57 

Ulmus  americana , food  plant  of  San  Jose  scale 38 

campestris,  food  plant  of  San  Jose  scale 38 

sp.,  food  plant  of  San  Jose  scale 38 

Yermorel  nozzle,  for  spraying  lime-sulfur  wash 75 

Viburnum  cassinoides,  food  plant  of  San  Jose  scale 39 

opulus , food  plant  of  San  Jose  scale 39 

sp.,  food  plant  of  San  Jose  scale 39 

Virginia  creeper.  (See  Ampelopsis  quinquefolia.) 

Vitis  sp.,  food  plants  of  San  Jose  scale 39 

Viviparous  habit  of  San  Jose  scale 43-45 

Walnut.  (See  Juglans  nigra , J.  regia,  and  J.  s ieboldiana.) 

Willow.  (See  Salix  sp.,  S.  pentandra,  and  S.  babylonica.) 


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